My latest fantasy book takes place in the City of O. O is it's name because O curves back on its self infinitely, just as the city of O does.
O is made of Chaos Matter, or as the natives call it, "Put" (short for Putty). A person will a bit of willpower and imagination can force Put into whatever shape they want. The harder they concentrate, the more the Put becomes what they want.
There are four general kinds of people in O. Willes: These folks are the suckers who just float through in life. None actually live in O, because as soon as they show up, they dizzolve into the Put, unable to keep their 'self' intact.
Aliens: People visiting O for any number of reasons.
Willworkers: Citizens of O who are capable of shaping the Put. They're artisans, reserchers, or just people enjoying their retirment in O.
Forces: Forces are deadly. Stay away from them. A force is someone who's personality, who's force of will can shape the fates of nations in their homelands...and can shatter the universe in O. Forces that have lived on earth are people like Hitler, FDR, Martin Luther King, and so on. If they had visted O, then they'd have become exponetially more powerfull...as long as they stayed there. Which is why Forces only stay in O for short times, creating what they need, then heading back to their home lands to do what they wish.