Who, alive today, will still be famous in 500 years? It’s the kind of question people might ask at dinner parties during a lull in conversation. But it’s one I’ve been pondering for the past couple of years, while writing a novel about three men who were together for a six-month period of bloody battles and lavish parties in central Italy. The story, set in 1502, is almost entirely a true one. The names of the men? Cesare Borgia, Niccolo Machiavelli and Leonardo da Vinci.

When I first read about this little-known moment in history, I was amazed that the three men should have known one another. In fact, Leonardo was working as Borgia’s military engineer, while Machiavelli had been sent by the Florentine government on a diplomatic mission. But I had never thought of them as contemporaries, perhaps because they are famous for such different reasons. Indeed, two of the three are really infamous rather than famous, and—thanks to the vicissitudes of time and rumor—they are remembered for things they probably didn’t even do.