City of a Thousand Suns is a 1965 science fantasy novel by Samuel R. Delany, and is the final novel in the Fall of the Towers trilogy.As in the other two books, the setting is the post-apocalyptic empire of Toromon, confined by a surrounding "Barrier" of highly-radioactive land, and inhabited by mutant/evolved "forest people" (some of whom are telepaths) and devolved "neanderthals", as well as normal humans. The events of the book focus on a claimed war.