I'm looking to identify a book.
The protagonist was the world's only immortal man who had been made immortal by some undefined process. IIRC he had been a basketball player as it had been assumed that over time the race would get taller.
The setting was semi-African in that I seem to remember them riding trained lions.
The main thrust to the story seemed to have been that someone had discovered his background and was trying to track down who he was.
I also seem to remember it ending with him being sealed into a crystal tomb, with his (non-immortal) girlfriend and having to eat her (!) to give himself energy reserves before putting himself into some kind of suspended animation.