Shamlegger Street
Shamlegger Street is the heart of Morpork's infamous Shades district, where even the criminals fear to go and the Watch didn't venture (at least until recently), even in groups. Strangely, this milieu produced the Vimes household's urbane and polished butler Willikins, whose unexpected prowess in hand-to-hand combat developed in his time with the Shamlegger Street Rude Boys (a fearsome street gang similar to his future master's Cockbill Street Roaring Lads, although both sides had a truce during their existence). An even less likely resident was Tooth Fairy Violet Bottler, who must have stashed her coins elsewhere, although the gift of invisibility while in costume and on call would help.
The city map is rather bare and poorly annotated in the nearby area; apparently no one could be found to go and have a look.