From the publisher:
City Builder Volume 11: Underworld Places is the final volume in a series of 11 complementary books designed to help guide Game Masters create exciting and compelling urban areas and places within them for their campaigns. It is a universal game resource that is not specific to any particular system and is intended to be compatible with the needs of almost any ancient, Dark Ages, Middle Ages, Renaissance, or fantasy milieu. Its contents include:
An Introduction that describes the series and how to use the material in this volume;
Sections devoted to Brothels, Gambling Dens, Pit-Fighting Rings, and Thieves’, Assassins’, and Beggars’ Guilds; and,
Two or more Adventure Hooks tying in with each described sort of place.