Ankh-Morpork

Ankh-Morpork, Ankh-Morpork, the city so good they called it Ankh-Morpork.

Features of Ankh-Morpork

The Mended Drum
The Palace, where you can create clubs and families, and read the non-guild boards
The Dysk, where you can watch plays written by players or write your own
The Apothecary Gardens, where you can join Pishe, buy more lives, or simply swim around
A real estate agency where you can bid to rent a house or shop
Offices for both in-game Newspapers, where you can buy papers or do reporter/editor activites
Two vaults where you can store your items--Nella's south of the Plaza of Broken Moons, and Jonas's in the north part of the city, somewhat east of centre, on The Ridings
The Shades, where you can get your weapons stolen and your throat slit

Ankh-Morpork also has a place for each guild:

The Assassins' Guild
The Thieves' Guild
A temple for each worshippable deity (Scoone in the Temple of Small Gods will take newbies to any of these), where you can become a follower or join the Priests' Guild
The Ankh-Morpork Palace Guard (a specialization of the Warriors' Guild)
The Weapon Masters' Court (a specialization of the Warriors' Guild)
The house of Gennie Applebottom, who can help you join the Witches' Guild
The Unseen University (Wizards' Guild)

Ankh-Morpork Council rules
Theft by non-thieves is punished by Thieves Guild heavies (npcs) with escalating punishments for repeated offenses.
Various other things are punishable by the Watch if you are seen doing them. (Watchmen will pursue you and tell you to surrender/give up and then attack you after a short wait. You can "give up", at which point you're sent to jail for a time (which varies based on what you did and how much), then let out.) These things include:
- Attacking a watchman
- Fighting in public
- Impersonating a watchman (presumably wearing their stuff/badges)
- Insulting a watchman
- Molesting a watchman (as described in the "felt the force" achievement)
- Murder
- Public miming
- Resisting arrest
- Vandalism (tearing down wanted posters or breaking street lights)
Witches singing the Hedgehog Song get prosecuted by the musicians' guild who do not refrain from corporal punishment including death.