Complete Guide to Psychonian Citadels

Citadels are the Psychonian replacement for cities built in early years after the many apocalypses. They are built to resist invasion by land or air, clouds of toxic gas that pass for weird weather and to hold a community together. Sometimes the current occupants are not the original ones. Conditions and functionality of systems vary based on the civilization occupying them. Open cities like ancients do exist but have problems. Shelters are the main requirement of any community on Psychon from caves to build bunkers or using ancient sub road tunnels.

You might want to connect it to a subworld or use elements from that. Or use space hab modules here also. Tables to generate a citadel are below.

Psychon citadels range from 7-50 stories tall with population equaling stories times d100. Short ones also called zigurats or arcologies. Could use some of this for surviving domes of ancients too. Bottom most floors are for defense and foreigners. Other floors may be dedicated to temples or what passes for magic schools. Libraries, food production, sport arenas, schools, and many other dedicated functions. Citadels are sealed against Psychon’s weird weather. Underground stores, shelters, connections to ancient sub train tunnels, morlocks or other creature lairs.

D100 Psychonian Citadel Events
This is to be used by adventurers staying in the citadel foreign and mercantile quarters. I have done this in a way to be usable in other settings too. For more tech oriented bunkers and subworlds see other posts. 
1 Thief tries to rob party
2 Organised crime spy on party for profit opportunity
3 Organised crime try to infiltrate party with sob story or offer of service
4 Criminal gang wary of power balance of land try assassination of party
5 Faction plant evidence on party to pin a crime on them
6 Eyes spy on party through air ducts
7 Feral children take a interest in party
8 Local vermin menace party
9 Local beast follows party
10 Scruffy beggar offers to tell party secret or story of treasure
11 Local scholars seek knowledge of distant lands
12 Local scholars and magicians seek knowledge of foreign magical arts
13 Local bards sing of heroes virtues and deeds
14 local bards sing mocking dirty stories of party
15 Local magician wishes to talk with party and possibly accompany them a while
16 Local seeks to duel foreigners to assess fighting arts
17 Local magician seeks to challenge foreign magicians
18 Local seducer seeks romantic entanglement with exotic stranger
19 Local slaver thinks party hot property tries trickery or ambush
20 Local healer seeks to learn on foreign medical practices
21 Local zealot cries for with hunt against parties
22 Disease outbreak, foreigners blamed
23 Murder outbreak, strangers blamed as killers
24 Horrible local parasite or fungal infection
25 Building collapses on party
26 Floor collapses into forgotten catacomb
27 Fire outbreak endangers party
28 Flood of water, possibly damages property and drowning
29 Strange weather outside affects where party staying
30 Local party animals seek strangers for good times
31 Moral crusaders preach about interacting with outsiders
32 Local foodstuff spreads disease or poison to strangers unused to it
33 Strange noises heard from drains and air vents
34 Secret society seek to spy on and kill strangers
35 Hidden cult seek foreign sacrifices nobody will miss
36 Hidden monster living in bowels of city want a party member or possession
37 Ghost seeks help or revenge from strangers so it can rest
38 Poltergeist or spirit angered by strangers
39 Doppelganger in disguise tries to infiltrate party
40 Rival adventurers constantly challenge party to eating, drinking or dancing or music contests
41 Rival party boast they can perform greater deeds of glory
42 Rival party arrested for doing simular deeds to party
43 Rival party has old friend or family member of party member
44 Rival party has old enemy of party member
45 Rival party hostile and seek to kill and rob party
46 Bounty hunters seek party from past deeds
47 Shape shifting monster seeks to rob party
48 Priest and cult assassins pose as adventurers seek party sent by wicked gods
49 Undead horror from crypts below interested in party
50 Dormant artefact awakens in presence of a party member
51 Innkeeper offers cheap priced crap left by adventurers
52 Innkeeper has some funny old potions for sale
53 Innkeeper has a thing in the basement causing trouble
54 Innkeeper has a troubling customer he wants help removing
55 Innkeeper offers reward for recovering debt from bad customer
56 Creature or local tries to charm party member with spell
57 Creature or local tries to curse party member
58 Creature tries to infect party member with it’s horrible offspring
59 Creature lays eggs in party baggage
60 Local secretes something valuable in party baggage
61 Local leaders have quest for adventurers
62 Local leaders have a fugitive that needs hunting
63 Local leaders have problem in citadel and cannot use locals
64 Local leaders put out warrant for party fir upsetting status quo
65 Local leaders need heroes to slay a creature disrupting local citizens
66 Parents offer adventurers their children as apprentices for discount
67 Parents offer adventurers their children for marriage for discount
68 Slave broker offers cheap slaves for crazy discount low low prices
69 Mercenary broker offers discount rates for local missions
70 Local bard offers to accompany party for a while for inspirations
71 Government tax collectors claim % of party cash
72 Government demands licence fees for weapons, adventuring, looting rights, etc
73 Government customs officials inspect party baggage for unwelcome imports
74 Government agents interrogate party looking for spies or security threats
75 Government law enforcers interrogate party looking for criminals and fugitives troublemakers
76 Child or pet falls down drain or well
77 Something from drain or well grabs child or pet or attractive youth and drags to depths
78 Floor collapses into catacombs where creatures lurk
79 Creatures dwell in secret using secret doors and air vents to spy and kidnap people
80 Secret morlock enclave kidnaps victims for cannibalism and slavery target party
81 Secret lycanthrope sect seek to blame party for murder sprees
82 Serial killer plants evidence of party on murder victim
83 Diseased or parasite animal bites party member
84 Party exposed to diseased waste or sewerage
85 Gang targets party with abuse looking for a rumble
86 Local festival of food and drink and wild parties
87 Solemn religious parades and prayer, business closed
88 Statues of gods led through streets, feasting and festivities
89 Day of mourning, funeral rites and feasts
90 Gift giving festival, visitors expected to be involved in local customs
91 Find strange unrecognised relic of the past in market place for sale
92 Find ancient text and art and maps on walls in form of relief artwork detailing lost loot
93 Find ancient manuscript in market or library describing local ancient ruins
94 Find ancient map of sub-world on back of recycled document or artwork
95 Find scrolls stuffed inside mattress or pillow
96 Cursed items for sale in market place
97 Riot breaks out in market place due to local tensions, party caught in middle
98 Shortages or food or lodging or water make prices and availability steep
99 Beggar offers to show secret subterranean catacombs under the citadel
100 Clue discovered to open ancient gateway hidden in citadel

Citadel GenerationThese are to help you generate citadels which should inspire plenty of adventure for many sessions of play.

Locations in citadels
You could allocate locations you think your citadel needs first and roll extra or roll them all. Location sub tables are merely standout features of otherwise typical features in citadel planning. Sub levels and ground floor may have multiple section per level but most others equal a floor or story. Low tech citadels use muscle or steak powered elevators or stairs with elevators and even gravity tubes for more advanced. Not all locations are as specialized as sub tables show so feel free to use more generic areas or develop your own or hybrid results.

Sub levels 1d4+1 You may assume power, cisterns or storage and roll rest
Ground floors 1d4+2 You may assume a gatehouse and roll rest
Mid levels 1d4 x 1d10 You may assume a ghetto or middle housing and roll rest
Upper levels 1d12 You may assume a palace for rulers and roll rest

D12 Citadel  Zones - Lower Level
These levels deal with the outside world the most and are bristling with arrow slits, gunports, turrets, gates, battlements and weapons. The heavy fortress defences are heavily patrolled and separate gates for locals and foreigners are normal.

1-3 Defence
4-5 Merchant
6-7 Foreign
8-9 Manufacturing
10-12 Ghetto

D12 Citadel  Zones - Mid Level
These levels are the basic living areas of the bulk of the population and industry that keep citadel alive. Less accessible to outsiders some citizens never leave this area.

1 Merchant
2 Church
3 Library
4-5 Greenhouse
6-7 Manufacturing
8 Ghetto
9-11 Middle Housing
12 Stadium

D12 Citadel  Zones - Upper LevelThese levels are for the elites and rulers of the citadel often forbidden to lower residence. Foriegn diplomats or great heroes or merchants may be welcomed.

1-2 Middle Housing
3-4 Church
5 Library
6 University
7 Museum
8 Stadium
9 Garden
10 Merchant
11-12 Palace

D12 Citadel  Zones - Sub Level
Underworld levels are hidden areas often with dangerous or unappealing places best kept out of sight. They are prone to being forgotten and even may have other populations or creatures dwelling in them. Most citizens think sub levels are dangerous and unpleasant.

1 Cistern
2 Mine
3-4 Catacombs
5 Garden
6 Greenhouse
7 Shelter
8 Storage
9 Ghetto
10 Power Station
11 Transit Tunnels
12 Dungeon

d12 Catacombs
These ancient tunnels have had various uses and are a maze of mostly roughly hewn and seldom used. Storage of the dead and occasional hiding place is what most locals think. Usually spooky, dank and unwelcoming. May be far more ancient than citadel or apocalypse. More modern citadels recycle dead for food or fuel or sell them to morlocks.

1 Niches with skeletons
2 Niches with coffins
3 Piles of bones often arranged in macabre stacks
4 Bundles of human remains
5 Mummified bodies in niches
6 Artwork depicting gloomy afterlife
7 Graffiti some very ancient
8 Insignia and shrines of long lost or hidden cult
9 Signs of habitation by criminal gang
10 lair of some kind of monster that has found a home here
11 Signs of a sweatshop
12 Stone sarcophagi

d12 Church
Temples are used but people to worship gods in most cases but could include shrines to ancestors, the state, the rulers, abstract philosophical concepts. Some may have specific roles and clientele. The popular faiths are generated with the civilization of a hex but these represent more dedicated centres of belief in citadel.

1 A tiny shrine with idols, simple stone slab altar or artwork in a niche or small room
2 A small church with room for a dozen worshipers and accommodation for holy teacher
3 A temple with room for up to a hundred worshipers and several staff
4 A cathedral with room for up to a thousand with many chambers, staff and artworks
5 An abandoned shrine to a long lost cult mostly dust covered
6 A hidden shrine with disguised entrance to secret cult chamber
7 A shrine which acts as a place of healing
8 A mausoleum with hundreds of interred dead and a chapel
9 A monumental scale work of devotional artwork such as a huge statue or stained glass
10 An oracle where locals come for divination, prophecy and advice
11 Monastery or nunnery where devotees live lives of simplicity and contemplation
12 A fully functional temple where holy folk commune with a god with holy guardians

d12 Cistern
This is usually simply for water storage but also includes waste and sewerage possibilities. Most have water stores or wells and sewerage but these represent larger more eficient functioning examples.

1 Huge vaulted water supply of good water with many chambers connected by arched tunnels
2 A maze of sub canals with dock with boats used for transport
3 Huge wells going deep into subterranean water filled caverns and waterways
4 Chambers with underground springs and crystal deposits
5 Spectacular ancient bathhouse with steam rooms and swimming pools
6 Fungus garden of exotic narcotic and edible stuff lit by dim phosphorescent glow
7 Huge cisterns full of sewerage, possibly flammable gas and unwelcome creatures
8 Sewer tunnel complex like a nightmare maze crawling with critters
9 Water treatment area where contaminated water stored and filtered
10 Slime encrusted grotto overgrown with strange growths from tainted water
11 Garbage filled cistern filled with citadel trash and drain water and sewerage
12 Lair of someone or something uses water for secret movement beneath citadel

d12 Defence
These are to defend city from invaders and often manned by soldiers, police, agents or militia. They are usually serious places and unwelcome to visitors. Most citadels have most of these especially a front gate but subtable results equal far more examples than needed.

1 Guardhouses everywhere to police area, often with view of outside and alarm device.
2 Gatehouses with massive doorways and mechanisms possibly murder holes and traps
3 Lockup or stocks where vagrants and miscreants and enemies are temporarily detained
4 Observation towers with view of outside or a district with communications of some kind
5 Recruiting centres where new troops are trained and drilled and drafted from populace
6 Barracks where troops eat, sleep when not on duty
7 Armoury is a guarded store house of armaments and weapons and repair facilities
8 Drill hall or square where troops march and perform drill in large open area
9 Secret police HQ is well defended complex where spies, assassins and other agents work
10 Martial art school where some specialist school of fighters train under a master
11 Training area with firing range, commando course, test dummies and other aids
12 Garage or stables for mobile defence forces

d12 Dungeon
Intended as a grim place of imprisonment may include areas abandoned to unwelcome creatures and persons having overtaken abandoned areas. Most regard with fear and trepidation. Most have at least some cells if not dedicated high population facility. Banishment or execution is a lot less effort and cheaper.

1 A huge prison with cells, work yards and security gates and barracks
2 A huge maze of torture equipment and cells with imprisoned victims in appalling conditions
3 A mental hospital where mentally ill are kept in despairing conditions
4 A hospital where deformed, disfigured, disabled and mutants are kept in horrible conditions
5 A sweatshop of imprisoned labourers usually chained at workbenches
6 A workhouse for orphans, single mothers, delinquents and other unwanted youths
7 Slave yard where slaves work and are sold and bred, possibly of a different people
8 A cursed series of catacombs overrun by undead and supernatural evil
9 Overrun by creatures and monsters of all sorts and long abandoned by citadel residents
10 A hidden complex of morlock kidnappers eating citizens in secret
11 Humanoids like goblins or kobolds have taken over area as a homeland
12 Heavily sealed and trapped, something sealed in here best forgotten long ago

d12 Foreign
This is where outsiders who visit for trade and diplomacy come to do business with citadel occupants without the citadel being contaminated. Aliens are usually documented and given passports for duration of stay and are often unwelcome outside this area or given limited access beyond. Only local merchants and brave locals mingle with foreigners. Some cities are more tolerant of foreigners living among them, others dont even let them inside. Dedicated foreign districts mean more trade and tolerance.

1 Embassy where a foreign power officials dwell for international affairs
2 Enclave where outsider culture practice own way of life, microcosm of foreign culture
3 Inns where foreigners stay while visiting often in groups for guests of varied status
4 Taverns where foreigners and locals mingle over food and drink
5 Brothels where exotic prostitutes cater to tastes of many lands
6 Custom house where foreigners are registered and taxed
7 Quarantine hospice where diseased or those suspected of disease are kept
8 Schoolhouse where languages and customs of citadel or other lands are taught
9 Zoo where foreign beasts are kept for amusement or out of suspicion
10 Fairgrounds where travelling carny and circuses set up their seedy excuses for fun
11 Slavemarkets where foreigners can be bought and sold
12 Warehouses of foreign goods are stored

d12 Garden
A place of recreation, beauty and education to be enjoyed by better class of citizens. Some places prefer fungus gardens, especially if underground. Gardens are for recreation and science rather than feeding a whole community.

1 Pleasure garden with scented edible plants, narcotics and roaming prostitutes
2 Herbalist garden where scholars, cooks, pharmacists and herbalists grow exotic supplies
3 Drug crops often guarded and exclusive to elites or sect
4 Sporting green for games and competitions of all kinds with snack stalls
5 Children’s park where kids and carers frolic with harmless creatures and gentle trees
6 Botanical park where plants of many lands are kept for educational purposes
7 Zoological park where beasts many lands are kept for educational purposes
8 Lovers park where youths come for holding hands and other liaisons
9 Theme park with extravagant entertainment, rides, stalls, clowns and other fun
10 Abandoned park gone feral with unwelcome beasts and gangland fights
11 Royal park where elites only frolic amidst tasteful decor and artwork
12 Water park with streams, ponds, thermal springs and exotic fish in tanks 

d12 Ghetto
These areas are dwellings of poorest, often overcrowded, dangerous, polluted and miserable. Some are a different race or ethnic group to typical citizens. Some citadels have no poor classes. In others the poor are expendable slaves.

1 Orderly worker barracks where dwellers shuffle of despairing to workshops daily
2 Cottage crafters where dwellers operate light industry and sleep among workbenches
3 Crime filled gang turf neighbourhood where lawmen and other services avoid
4 Horrible area with decaying buildings and disease ridden starving inhabitants
5 Old neighbourhood with mostly geriatric population few young desperate to escape from
6 Open gang war with kidnapping, murder, extortion and frequent brawls
7 Controlled by local gang who charge tax and act as officials and run best black markets
8 Powderkeg of dissent with revolutionaries and demagogues driving people to boilingpoint
9 Cruel police suppress this area due to constant riots. Brutality drive resistance underground
10 Fire trap frequently redeveloped and rebuilt with new fires being common
11 Rebuilt by well meaning officials but flawed and already in decay
12 Strong folk community who take care of own live charming idyllic cultured lives

d12 Greenhouse
These areas provide food, requiring natural light, artificial life or crops that do not require light like fungi. Citadel may have outside crops too but when weather bad for months or terrain harsh, indoor farms do better. Without these food is more costly, boring and scarce. Trade can provide some food in bad cases but food shortages tend to shrink the population.

1 Monoculture of single crop with specialized tools and chemicals and labour
2 Mixed gardens with many variety of crops and animals
3 Eco garden which appears wild and unkept but is a thriving ecosystem
4 Hydro garden with crops grown in nutrient sollution
5 Aquaculture farm with fish, eels, lampreys and shellfish grown in tanks
6 Bug farm with insect and larvae farming, often low maintenance
7 Wild greenhouse of savage ecology mobile plants or fungi
8 Algae farm grown for food and biofuel
9 Soylent green processing plant where miracle manna made to secret process
10 Overgrown with toxic slimes and fungus and inhabited by unwelcome creatures
11 Culture farm where huge vats of bacteria and yeast bubble constantly
12 Huge bloated humanoids plumbed into refinery producing nutrient

d12 Library
A depository of wisdom, learning and culture for citizens and scholars to access data. All literate cities have small ones at least and some bookshops. Some restrict who is able to read and use books. Some censor books stockpiling some but burning most.

1 Huge collection of dusty tomes in a maze of enormous shelving
2 Scrolls kept in tubes in collections in huge shelves
3 Scriptorium where documents are copied by hand by scribes
4 Tablet collection in huge shelves, tablets of clay, stone, jade and wood
5 A school for youths to learn basics of writing and technical trades
6 A monastery of holy folk rote learning lineages and poems handed down through time
7 Citadel records of citizens birth, death, marriages, and other administrative records
8 Collection of relief art carved in stone or painted on walls or stele in galleries
9 Crumbling mess of damaged books, rotting shelves with no organisation and vermin
10 Ancient AI brain with huge data bases and programmer priests
11 Collection of networked immortal brains in serial holding collective wisdom
12 Computerised data stacks in banks or tape reel and card reading machines

d12 Manufacturing
A centre for making goods and refining materials. Provide work as well as luxury, trade goods and weapons. More industry equals more work.

1  Huge sweatshops where workers sleep and work for life
2 Industrial factory with rows of workers tending machines in unison
3 Robotic assembly lines with android workers in sealed system
4 Slave workshop with other race or species, visitors kept out
5 Huge smelting facility with men or androids or golems or morlocks toiling in horrendous heat
6 Huge workshop with separate cottage craftsmen skilfully making goods
7 Docile subhumans bred or lobotomized for compliant labour in sweatshop
8 Shoggoths imprisoned in great vaults working on all manner of goods
9 Huge mills with children scuttling among deadly spinning apparatus
10 Animals or slaves turning huge wheels powering mills
11 Gremlins, gnomes or goblins bound in sweatshop with enchantment
12 Steaming factory populated by morlocks in exchange for human flesh

d12 Merchant
This is principle area of commerce and trade where citizens obtain basic food and goods. Otherwise corner shops in housing estates are common.

1 Market square filled with barrows, pushcarts and wagons with small stalls
2 Warehouse district with huge stockpile of bulk goods available
3 Spacious clean post-industrial supermart with androids serving prepacked goods
4 Banks of atomic powered replicators creating food and goods operated by priests
5 Rows of tiny specialist shops in a mall with street vendor food and drinks
6 Rows of vending machines, actually with gremlins or goblins inside
7 Rows of vending machines, with variety of packaged goods
8 Automated warehouse with AI terminal and priest programmer as storekeeper
9 Department store with various specialist sections with individual sales staff
10 General stores with clutters of goods and crotchety old shopkeepers
11 Shifty blackmarket with goods sold off back of carts, no questions asked
12 Huge junk heap and plies of goods tended by crazy old man with big dog

d12 Middle Housing
Housing of middle classes including merchants, civil servants, officers and other skilled and educated persons. Most have private rooms, kitchens and many have courtyards and servants. Functional toilets and running water common. Privacy and leisure spaces are common for middle dwellers.

1 Rows of apartment blocks with doormen controlling access
2 Large courts with fine houses separated with gatehouses and gatekeepers who limit access 
3 Rows of multi story shared houses with nosey neighbours and patrolmen militia
4 Well to do large houses with courtyards with large families including students
5 Huge towers with automated elevators, laundry services heating and lighting
6 Decrepit high rise apartment with decaying walls and failing infrastructure
7 Large organic shaped open living areas with gardens and communal living space
8 Biological habitats with food growing from walls with ecology of cleaning critters
9 Highly mechanised apartments with labour saving devices built in
10 Family and extended clan communes with shared enclosed spaces
11 Subdivided decrepit old palaces size of city blocks turned into hundreds of units
12 Modular living habs built in stacks in huge clusters like giant children’s blocks

d12 Mine
Tunnel complexes deep in earth seeking precious resources. Many are long abandoned after construction of a citadel and over run by monsters. Working mines enrich a nation with resources and trade as well as provide jobs.

1 Winding hand carved labyrinth in stone following ancient veins
2 Mine shafts deep into earth and into natural cavern system
3 Even wooden beamed tunnel complexes winding methodically into the earth
4 Incredible maze of tunnels with remnants of rail systems, pipes, beams and miner housing
5 Concrete supported tunnels with remains of mining machines
6 Buzzing with activity complex full of kobolds, goblins or gnomes or morlocks
7 Active mine pit with clockwork bronze automatons or golems or robots or androids
8 Otherworldly beings like elementals or devils toiling earth resentful of human spies
9 Slaves possibly bred morons or of other race to citadel working selves to death
10 Long abandoned mine system overgrown with fungus and crawling with subterranean life
11 Colossal cavern with giant machines or giants or cyclopses working at seams
12 Tunnel complex dug by titanic worms burrowing deep into earth

d12 Museum
Museums house collections of cultural and educational artifacts of interest to public and scholars alike. Some are popular thriving cultural landmarks that tell the story of a people. Others are dusty, musty and forgotten shambles. Some hold forbidden works kept hidden. Some cities have no cultural facilities and are impoverished culturally.

1 Historic artefacts telling story of the citadel and its denizens through the ages
2 Apocalypse museum telling story of the fall of the ancients containing borgs and weapons
3 Museum telling what local experts believe ancients lived like before apocalypse
4 Art museum of paintings, sculpture and fine design of citadel and other lands
5 War museum of cities battles and struggles of the past
6 Heroes museum of leaders, scholars, magicians, athletes, warriors and holy folk
7 Black museum of hidden lore, well guarded and filled with alien relics of the elder gods
8 Natural history museum of stuffed animals, meteors, fossils, bottled creatures and insect displays
9 Museum of erotic culture with displays on sex from many cultures and species
10 Space museum with retro space suits, re-entry pods, rovers, alien heads in jars, flying saucer
11 Industry and industrial museum with displays of tools and technical progress
12 Propaganda museum of how citadel superior to other civilizations

d12 Palace
These are habitats for leaders and social elites. Most are luxurious and glamorous but a bit tacky. Some are run down and decayed and even have unwelcome tenants. Most citadels have some flash pad for elites of some kind.

1 Fabulous throne room for leaders to impress the common citizens with processional stairs
2 Private royal palace for ruling clan with gilded furnishings and hundreds of paintings
3 Fabulous crystal palace of special grown crystal with strange holographic echoes of past
4 Harem palace for consorts of elites and their children heavily guarded
5 Palace of justice with courthouses, execution facilities and holding cells
6 Hotel for foreign dignitaries, rich merchants and locals wishing a taste of luxury
7 Casino where locals lose money in opulent setting
8 Run down palace for older retired dignitaries and officials
9 Assembly hall for leaders to debate law and public policy
10 Palace for elites with hundreds of secret passages and rooms hiding some awful secret
11 Palace for religious or spiritual leaders filled with art and symbolic designs
12 Ruined ancient palace long sealed with unwelcome animals and monsters

d12 Power station
These areas act as power supply for city systems, resident electricity and mechanical or motive power for industry. Chemical engines, steam, geothermal, atomic, solar and wind are all common varieties. Some receive power beamed from space or even broadcast power to local systems. Some are long dormant and forbidden to enter. Usually guarded. Most cities have some power but dedicated systems produce richer civilizations with more automation, elevators, air recycling and lighting.

1 Huge fuel powered generators with massive fuel stockpiles of biodiesel, petrochemicals or coal
2 Atomic reactor slightly leaky with drums of waste stacked everywhere
3 Nuclear or fusion powered sealed low reassure safe system running smoothly automatically
4 Meat slurry fuel plant requiring corpses and animal remains to maintain
5 Solar battery supplied by conversion ells on citadel surface
6 Huge crystalline core plant draws power from hyperspace, adds mass to universe
7 Huge battery and antenna array draws power from planet or broadcast from space
8 Titanic shoggoth captured in vault manually cranks turbine
9 Tubes of algae throughout citadel surface grown and converted to fuel
10 Sewerage from population and animals converted to biofuel for generator
11 Geothermal plant with huge pipelines going deep into earth
12 Windmills turbines on citadel surface or subterranean water turbine or wavefarm

d12 Shelter
Shelters are to keep population safe from conditions on surface in the event of war or a new apocalypse or severe weather. Most have oxygen filters and some serve specific purposes. Citadels are inherently a shelter but even they need back up plans.

1 Science bunker where scientists work on weapons of war, possible remnants of research loose
2 Huge chambers for general population for a week or so
3 Bunker where elites can survive for hundreds of years
4 Bunker for elites has been forgotten and overrun by unwelcome creatures or entities
5 Bunker with automated clone banks to create new race if occupants killed
6 Bunker has been forgotten with former citadel folk in hibernation
7 Bunker overrun with organised crime gangs
8 Shelter used by secret cult for forbidden rites of evil
9 Morlocks or goblinoids or mutants dwell in secret preying on citadel population
10 Contaminated frozen undead, mutants or worse ready to arise
11 Used by political faction to prepare army of terrorist or revolutionary thugs
12 Past population came down during disaster now in hiding or unaware of outside

d12 Stadium
Public spaces for entertainment and leisure and contests of various types provide residents with social opportunities. Without these a city is much duller but most citadels have at least a square or meeting hall for gatherings.

1 Huge square for rulers to address public rallies with podiums
2 Huge gladiatorial arena for blood sports with men and beasts
3 Race track for vehicles (like chariots or jetbikes) or beasts
4 Fighting pit for lowbrow dirty blood sports many illegal
5 Green sports field for games like stickball and kickball
6 Waterpark with pools for leisure,  racing and aquatic games
7 Park with obstacle course and playground equipment for adults and children
8 Speakers square where public can hear various debates and talkers on soapboxes
9 Theatrical arena for dramatic and comedy performances
10 Public gymnasium with equipment and areas for track and field events
11 Rings for wrestlers, martial artists and duellists for training and public sport
12 Exhibition halls for craft competitions and trade shows

d12 Storage
Citadels have many storage needs and this area provides space for long term use. Most have warehouses. Some are so long forgotten new inhabitants or fabulous lost treasures await within. Some are well guarded by personal or technology.

1 Huge silos for citadel food supplies in long term storage
2 Cold store with huge frozen food warehouses
3 Huge warehouses for city trade goods and supplies
4 Storage lockers rented for citizens personal storage needs
5 Huge cryopod centre with frozen people, animals, embryos, animals, seeds
6 Shantytown of storage lockers where poor citizens live if can’t afford ghettos
7 Toxic waste depository with thousands of leaking metal drums and concrete blocks
8 Run down forgotten warehouse squatted by youth gangs or criminals or cults
9 Huge warehouse housing machinery abandoned due to part shortage or ignorance
10 Armoury for weapons decommissioned or forbidden by law or treaties
11 Huge cellars filled with bottles and barrels of wine and alcohol
12 Forgotten warehouse occupied by morlocks, mutants or monsters

d12 Transit tunnels
Tunnels used for transport of goods often remain from ancient times. Many are partially collapsed or forgotten. Some become habitats for creatures or secret places for hidden gatherings. A few tunnels for secret entry and exit or emergencies is standard.

1 Station for local tube train system to other local places of interest often in a loop
2 Station of ancient intercontinental vacuum sub trains long abandoned
3 Long forgotten pipelines for gas or fluids many now occupied by unwelcome creatures
4 Entry to natural caverns now crawling with life in dynamic ecology
5 Secret tunnels for military and government agents
6 Emergency tunnels for evacuations sometimes used by unauthorised persons
7 Tunnel complex for farmers to bring food and goods into the citadel
8 Long collapsed sub roadway now occupied by wild creatures
9 Tunnel complex dug by morlocks or kobolds or some other race
10 Tunnels used by locals but dug by giant creatures like worms or  moles
11 Tunnels to long forgotten subworld or ancient city
12 Tunnels to subterranean kingdom with artificial sun

d12 University
Most civilized people have schools for young and at least apprenticeships for adults. Universities are self contained micro communities often with own housing, libraries, council chambers, mess halls and even security. Many imose strictures like celibacy on students or make them wear uniforms. Some are exempt from military service some are able to be incorporated into units rapidly and perform cadet drills. Students may operate own councils, secret societies, publishing, clubs and sports separate from wider community. Some are recruiting grounds for elites, cults or crime or military. Some provide public services like hospitals or conduct research or maintain museums and libraries and children’s schools.

1 School for middle class residents to learn literate and technical trades
2 School for elites to learn sciences, arts and magical skills
3 School is a front for teaching forbidden black arts
4 District with clusters of private schools and tutors
5 Military school teaching elite troops and officers
6 Trade school teaching basics of industry and agriculture
7 Philosopher schools teaching debate and what passes for logic around here
8 Monastic school teaching with strict discipline
9 Research school with mammoth library and dedicated to advancement
10 Mad science facility with research into weapons and doomsday devices
11 Hospital providing healing for masses and teaching of healers
12 Arcane school teaching secrets of science and sorcery

Outside details of a citadel: Surface and surrounding area
The countryside around a citadel may have additional features. Roll 1d4-1 times on the surroundings suitable. Outsides of a citadel may have extra features. Some features of a city power plant might include outside of a citadel. A sub table for external features is optional but a d3-1 rolls might be useful amount of detail.

d12 Citadel surroundings
Many citadels abruptly stand in open but many more have surrounding countryside with some of these features.

1 Fortifications including sharpened stakes, tank traps, mines, trenches and walls
2 Farmland with farmers shacks and barns, people retreat in citadel in emergencies
3 Sprawling slum with crudely made dwellings with population usually not allowed inside
4 Water features with moats, ponds, lakes stocked with fish and waterfowl
5 Windmills or solar panels or salt ponds or algae lakes for power or fuel generation
6 Garden earthworks with fruit trees, strange follies, shrines and statues
7 Ruins of ancient city or abandoned town sprawl around city with unwelcome residents
8 Tents and wagons of foreign travellers and nomads who seasonally visit for trade
9 Pits of garbage, polluted discoloured pools, pits, mounds of dirt and other crap
10 Dense vegetation grown for food and defence including thorns and toxic plants
11 Biological slime lake of gelatinous goop, fungi or shoggoth matter used for food and defence
12 Open mine pits, factories, mills and other industrial structures possibly abandoned

d12 Citadel surface
Most citadels are highly ornamental with spires, towers, statues, gargoyles and and other ornaments. Here are some common variations.

1 Defences bristling with battlements, turrets, guns, towers, observation posts and guards
2 Vegetation with food and industrial resources with animals and birdlife and streams
3 Wind mills or solar panels or algae tubes for power production
4 Highly reflective shiny glittering surface resistant to energy weapons
5 Force shield wall of energy protecting citadel from threats
6 Scared pitted ruined appearance from battle and environmental damage
7 Organic coral or flesh or vegetal coating giving citadel natural appearance
8 Rocky coating resembling natural stone formation possibly keeps hidden
9 Covered in antenna, dishes, radar domes, cameras, neon signs and electrical transformers
10 Crystalline tiles or solid sheathe coating highly impervious and beautiful
11 Shambling huts, shacks and tents of impoverished class
12 Magnetic field containing plasma or magical energy field for defence

I will generate a few examples soon - quite pleased with this and would love too see results of anyone using it - happy new year!