This is something I have been working on for years, taking the cities of town of Mystara and converting them to 2nd Edition rules and giving them the Forgotten Realms Adventures treatment and adding my own twists and NPCs. Here is Threshold as an example (and by the way, I have removed 99.9% of the Immortals concept and "standardized" them with deities and churches, and yes IMC Aleena is still alive):
Threshold
by Brian CarawayFortified Town of The Grand Duchy of Karameikos
Who Rules: Patriarch Sherlane, Baron Halaran (LG hm C14 of Diulanna); a kindly, aging priest who is quite friendly to his populace, but shows little mercy to the disrespectful or anarchic.
Who Really Rules: Duke Stefan Karameikos, to whom Patriarch Sherlane has sworn allegiance. The Duke's Law, along with a few stipulations, is strictly enforced here.
Population: Approximately 8,000 in winter, to 12,000 at the height of the summer trading and adventuring season.
Major Products: Fish, lumber, cloth, trade.
Armed Forces: The Town Guard; 300 F1s in chainmail armor and shield, armed with shortsword and club; 30 F4 sergeants, and 3 F5 lieutenants, commanded by Captain Ivan "The Serious" Fyordorov (LN hm F9). The guard patrols in squads of ten or twenty, depending on whether it is day or night, with a sergeant in command.
Local Laws: Within town limits, no mage spells may be cast. Any offenders caught will be brought up in court at the Halls of Justice, where if convicted the guilty party will have a curse bestowed upon him, unless the court can be convinced that there are mitigating circumstances:
First Offense: loss of hair, skin turned green in color or unsightly pimples or facial hair. This can removed by any priest's remove curse spell, but the offender must keep the curse active for at minimum one day before having it removed.
Second Offense: insomnia for two weeks (makes rest or regaining spells impossible (This can only be cured by a remove curse spell cast by a cleric of 9th level or higher)
Third Offense: struck dumb, no spellcasting for one month (can only be cured by a remove curse spell cast by a cleric of 12th level or higher)
Fourth Offense: indefinite incarceration below Tarnskeep.
Aside from these additions, the Duke's Law is the law for this town. Threshold is a peaceful town where (with the exception of Fogor Isle) anyone can walk the streets at night, and Patriarch Sherlane wants to keep it that way. To this end the only weapons which may be carried in town are swords, daggers, and staves, and any swords and daggers are peacebonded. Prohibited weapons are confiscated by the town guard and kept in town hall. The weapons are returned when the owner decides to leave town, then they are escorted to the town gate by two guardsmen and a 4th level cleric. Also, while not illegal, the wearing of armor is frowned upon by the town guard and most of the citizens of Threshold. People can enter or leave town while wearing armor, but they will be constantly followed around and questioned by the town guard if they are seen simply walking around town openly wearing armor.
Notable Mages: Since mage spellcasting is outlawed within town limits, no mage has set up permanent residence in Threshold town proper. However, there are several mages who live in the surrounding countryside:
Alisan Lightstaff (LN hef W16), who runs the local chapter of the Karameikan Wizard's Guild, which is five miles north of town. There will always be at least 1-6 mages of varying power there (3rd-12th level) researching or studying spells, or tutoring wizards of lesser power (See Specularum for the Wizard's Guild).
Notable Churches:
The House of the Eternal Climb, temple to Diulanna (Adamantine High Priest Mathias Gantor, NG hm P15; 15 underpriests, 153 followers)
The High Hall of Fortune, temple to Beliaar (Most Fortunate High Priestess Nanilith Salanthas, NG ef P15; 5 underpriests, 34 followers). This temple (as most of those dedicated to the God of Luck) has a thriving gaming hall attached to it, which is open to the public at all hours of the day and night.
The Lady’s Healing Hand, temple to Mirrah (Master Healer Taren "Gentletouch" Dalanim, CG hm P14; 18 underpriests, 51 followers). This temple/hospital is situated between the north wall of town and Tarnskeep. They accept anyone for healing though a donation is expected, either in gold or services.
The Seven Chambers of the Heart, temple to Valerias (Platinum Bladeheart Aaranlin, NG hm P17; 16 underpriests, 74 followers)
The Halls of Justice, temple to Tarastia (High Justiciar Marcus Flavius Scaurus, LN hm P15; 12 underpriests, 38 followers)
Shrines to: Asterius, Koryis, Odin, Thanatos, Thor, and Tyr.
Notable Rogues’ and Thieves Guilds: The Kingdom of Thieves, The Veiled Society, and (secretly) The Iron Ring all have branches of their respective guilds in Threshold, although most of their operations are done on Fogor Isle. See the city of Specularum on further details of these guilds.
Equipment Shops: Partial, poor in winter.
Adventurers’ Quarters: With the constant influx of adventurers, wanderers and transients of varying kinds, there are almost always a boarding house or three to stay in as well as several inns, but the ones of note are these:
The Hook and Hatchet; inn and tavern (good/moderate): although the lodgings and food are decent, adventurers tend to avoid it because it is a known watering hole for the town guard.
The Silver Dragon; inn (excellent/moderate): This inn is an adventurer's home away from home; decent prices along with some of the best food and lodging in the region, run by Gareth Brendan (NG hm T13 [Acrobat kit]), a retired adventurer with varied connections throughout the duchy and beyond.
Beliaar's House of Gambling; inn and tavern (good/moderate): This is the gambling house attached to the temple, where a good part of Threshold's populace goes if they have a spare silver or two to wager. As part of their duty to their god, priests and followers of Beliaar work here.
The Lion Rampant; inn and tavern (fair/cheap): This inn is frequented by adventurers and those who don't have (or want to spend) a lot of money, and they get a decent bargain for what they pay for.
Important Characters:
Aleena Halaran (NG hf P7 of Valerias): She is Baron Halaran's niece and his right hand in most matters. She still adventures from time to time but it is becoming increasingly rare, due to her growing role in helping her uncle govern Threshold. Her duties have also kept her from seriously searching for a husband, thus she has not risen higher in ability and rank in the clergy.
Kenalas Silverstreak (CG hem R6/P7 of Solonor Thelandira): adventurer, local hero, and freelance agent for Baron Halaran. He also heads up an elven task force to keep the loggers from advancing too far eastward from Loggertown on the other side of the river.
Carrienna Brightflame (NG ef W5/T6 [Spellfilcher kit]): Fellow adventurer and wife of Kenalas. They recently have had a daughter, Myrya Silverflame, and is semi-retired.
Brother Thalan Eresandir (LN hm Monk6, S: monsters): A wandering soul who has made a semi-permanent home in the wilderness east of Threshold. His expertise on most monsters is invaluable to novice and expert adventurers alike.
Volkil "The Aggressor" (CG hem F13/W13/P13 of Solonor Thelandira): A retired adventurer and head of the Academy for the Advancement of Adventurers, along with his wife Marra (CG hef W(Illusionist)10).
Lieutenant-Commander Arthol (N hm F7): Also a retired adventurer, Arthol is now second-in-command of the town guard, and is usually the one who gruffly greets visitors to Threshold. He has an almost photographic memory, and can tell first-time visitors from long-time residents or those who come to Threshold often.
Important Features in Town: Threshold is a very large town for its population. By decree of Baron Halaran, no building or residence may be built within 50 feet of each other. This gives Threshold an open, airy, comfortable feel that is popular with adventurers. Its more notable features are:
Fogor Isle: Every city seems to have its dark side; a filthy, run-down den where even the watch fears to tread, and Fogor Isle is no exception to this rule. Many businesses thrive here and while some are legal, most are not. When night falls, this place becomes so dangerous that even the city watch does not cross the bridges to patrol Fogor Isle. The Kingdom of Thieves and the Iron Ring both have headquarters here.
Loggertown: On the other side of the Windrush River is an encampment of approximately 400 loggers who work the forest to the east. From time to time, the community hires adventurers to rid the forest they work of various monsters that harass them. They have an agreement with the Calarii elves that for every tree that is cut down, two shall be planted in its place. Also, they are not to advance their logging operation more than 10 miles away from the shore of the Windrush River. All in all, this place is a bit on the rough-and-tumble side.
The Old Mill: On the northern end of Fogor Isle stands the charred ruins of The Old Mill, which was the main sawmill until it was all but destroyed by fire in 985 AC. The ruin is home to various kinds of giant insects, and adventurers are hired periodically to clean them out until it can be rebuilt.
Lakeshore Town: This is a small fishing community of about 250 people.
Tarnskeep: This is Baron Halaran's personal castle; a small, sturdy fortress with a single curtain wall and a large manor house. This is also the secret place where the Duchy's silver pieces are minted from the silver ore that the Elvenguard brings upriver once per month. This is also where the more dangerous prisoners are incarcerated.
Town Hall: This huge five-story building dominates the center of town. It is here that town meetings are held, confiscated illegal weapons stored, public declarations made, and major entertainment and events are held.
Hutaakan Ruins: North of Threshold, on the western shore of Lake Windrush, stand the ruins of some ancient town; the walls still stand in places, and pieces of rubble dot the landscape. There are hard-to-find entrances to catacombs underneath the ruins, where it is rumored that undead and treasure still lie in wait.
Monastery of the Enlightened Ones of the Eastern Moon: In the Black Peak Mountains well to the north of town lies the secluded temple of the Enlightened Ones of the Eastern Moon. Master Chin Tai (LN hm Monk13) is the leader of this splinter temple (the main temple is in Ochalea). The trail that leads to the temple gates is long and fraught with all kinds of peril, but Master Xian realizes that those who risk their lives to come here either badly want to learn or are running from something. As long as the latter does not endanger the temple he and his lesser monks have built here, he will welcome and shelter them for a time. Also, every six months Master Tai holds a martial arts tournament on the grounds of the monastery, and seeks to make his splinter temple a center of martial arts learning and instruction away from Ochalea and the Pearl Islands.
The Academy for the Advancement of Adventurers: This stronghold is located at base of the mountains northwest of town, and is a haven and training ground for adventurers. Volkil and his wife Marra head a council of highly experienced adventurers that preside over the Academy, and they have recently started construction of a village that will surround the grounds of the Academy. Through an ingenious system of illusions and “real-threat” situations, the academy is fast becoming the premier place for adventurers of all experience levels to congregate, train, and share their experiences for the following generations. For a fee of 1,000gp times the experience level of the adventurer, a novice (levels 0-2) can train up to the third level in experience, and more experienced adventurers can train for the next level of experience. Volkil and his council have very close ties with Baron Sherlane, and think nothing of sending trainees of various levels to assist in patrolling the wilderness about both the Academy and Threshold proper, or assisting directly in the defense of the town in some way. It is not uncommon for a 3rd to 6th level adventurer to be seen accompanying a guard patrol.
Weir and Dam: The dam was built to keep boats from being able to travel upriver from Threshold; Baron Halaran sees that as the prerogative of Threshold residents only. The weir (a small screen used to catch fish) is used by Threshold fishermen; it can be dragged aside, and is whenever logs are coming downriver from Loggertown.
Local Lore:
Clifton Caldwell, a well-known merchant, has recently purchased the Old Antilles Castle five miles west of town. He has posted advertisements in most of the taverns and inns looking for "Qualified Eviction Personnel" (Module B9, Castle Caldwell and Beyond, standard adventure for character levels 1-3 or re-write for character levels 5-8).
A former priest of Tarastia named Elwyn, now turned to Alphaks, is rumored to be organizing a large raiding party of orcs three days ride to the east. Baron Sherlane wants this rumor investigated.
A foreign nobleman who owned a fleet of merchant ships was assassinated last week ago in Specularum. The Iron Ring is being blamed.
A merchant has been making some inquiries about something called "The Rock" (Module B7, Journey to the Rock, either standard or re-written for a higher level party).
When I started this project I of course did the larger communities of Karameikos and slowly started expanding outward. The issue I have is when there is only a small paragraph describing a community in a Gazeteer or module, and Pandius doesn't have much on it either (such as Dolos and Nemiston in Darokin) and I have to create it from scratch. It takes much more time, because my muse is a lazy beeotch most of the time.