- "Just picture a lot of pretty, colourful houses and things wound around a hill, with a cluster of grandiose almost white civic buildings on the crest."--Weft 
The Offwhite City is a city-state and the leading power on Weft's home planet at the time of the Twine Wars.
Its name was first given in-story by the monk Weft, who translated it (unofficially) as Whitish City. The official translation, settled upon later, is Offwhite City. There was a little ruckus involved in the process of making this the official translation. Quibbling over points of language is usual in Offwhite.
The actual name is 'City the colour of unbleached (insect) silk'; the inhabitants have a single word for the colour of untreated silk, much like English has for ivory or indigo. (We'll not call it Ivory City. That might give people dippy ideas...)
The Offwhite City is the only Instarrian civilisation we have heard about. Canonically, we know a few things about it:
- It contains many religious orders, including one monastery whose followers have been encountered.
- It's been indicated that the state has a fairly high degree of involvement in people's everyday lives.
- Gods and divinities do, at least to some extent, really exist there.
- Weft considers it "the most beautiful place in the world".
1. Structure and history
The city was built on a mountain, which was inconvenient for almost everyone involved. During the process, the many canals that surround the base were also built. A great deal of slave labour was used for this. (Slavery as a penal measure still exists at Twine Wars
time, but is less common.)
2. Outside the city
- "I was considering heading out of the city and getting an impression of some other parts of Instar." [said Nico] [...]
"But I don't think there's much outside," Weft said. "It's full of... of yuck and mud. And there's the sea. I don't think there's anything else unless you go to one of the colonies, and they're just not-very-good versions of the city." 
Most residents of Offwhite are a little better informed, but not much more positive, about life outside the city.
- Mutt: Suitov says they eat one-handed and use a spearing implement which, for simplicity's sake, we can say is pretty much like a fork.
Mutt: I don't mind, so I'll believe him.
Mutt: Weft says they'll probably bring some crunchy things (croutons) with the meal, if it has a lot of sauce or gravy, and they are tipped into the plate or bowl afterwards to soak up the sauce and are eaten.
Anke sensibly asks the question you're meant to ask of any fantasy city: where do they get their water? Mutt's been waiting for that one...
- Anke: I'm curious how the water is being distributed. Is there a central reservoir on the top of the mountain, or, well, how does it get up there?
Ankewehner: Big mountain.
me: Also, aqueducts, coming INTO the city, not out.
Ankewehner: Yeah, of course. Pumps in those?
me: I think gravity, with valves (to stop backflow). Not sure, but they have the resources to build Roman-style superstructures.
Nico: psst, boss, just because the city's built on a mountain doesn't mean that there are no higher mountains around... just as a thought.
me: There's running water, as in mains and taps, in the city. They don't use as much water as a Western nation does; people don't take showers or baths often.
me: It's actually pretty isolated as mountains go. Not part of a large range. But I did say the aqueducts were serious engineering.
5. Society and politics
- Disreputable was generally one of the first adjectives a new learner picked up, at the same time as prestigious, bad and good, legal and illegal, and of course fashionable and unfashionable.
- I thought, ok, what's a mild insult among these people? Ah, I know: "You take insufficient care with your personal grooming!" A major insult likely pertains to romantic habits, fetishes or extreme examples of dirt. A killer insult is, of course, calling someone a dog.
--Mutt, in chat
From what we have heard so far from Weft , there are two social classes: 'aristocracy' and others. Weft seems to use 'aristocrat' interchangeably with 'politician'.
There is also a division between citizen and non-citizen. Citizens can participate in the political system and become licensed craftspeople. Citizenship can be revoked.
5.1. Who is a citizen?
Anyone born in the city territory (to a mother who was there legally) is a citizen. Anyone born in a colony, or sent there as punishment, is not a citizen. Slaves are not citizens, but by Twine Wars era, slaves' children are citizens if born in the city territory. Monks
are not, legally speaking, citizens.
Non-citizens are not allowed in the city, unless they're a slave and supposed to be there.
5.2. Health and illness
Mental illness is considered just as transmissible as bodily illness.
6. Technology and transport
Barges in the lower city.
Taxis are pulled by ostriches.
They have printing presses, generally water-powered (the city having a cheap and reliable source of water power). These are all government-owned.