The Cobblestone Beat
There may be other places called wretched hives of scum and villainy, but none have organised themselves quite so well, nor made quite as much profit as the City of Ankh-Morpork. Unfortunately, Lord Vetinari and the City Watch have the task of riding herd on all these sweltering masses yearning to breathe something besides the stench of the Ankh River in high summer.
As a city that has earned its reputation by catering to all manner of living, and un-living, persons (or un-persons) and creating equal opportunities for all to be mugged, blown-up, turned into a toad, preyed upon, take a pie to the face and otherwise pursue happiness, it is only a matter of time before something threatens it's very existence.
Not to worry though. The Ankh-Morpork City Watch will almost certainly come to sort things out. The Modern Watch is very efficient at these things, and now-a-days hardly anyone is wrongfully imprisoned, falsely accused, or worse yet, disintegrated by a troll wearing a badge and carrying a siege crossbow...