The Immortal of World's End

Earth's last continent is Gondwane, all the land there is left, and Ganelon Silvermane was made for it: a genetic construct, young and yet of great age, built to hold a shattered humanity together. This third instalment sends him against a city of illusion, the scientific immortals and a horde of the world's ultimate barbarians. DAW issued it new in 1976, under a Michael Whelan cover.