Biology and the foundation of ethics Book

This is a novel that I love to return to.

Baudolino, a self declared liar tells the story of his life to a Byzantine court official and historian who he has rescued from the sack of Constantinople during the fourth crusade (1204 AD).

Baudolino's story takes in the life and career of his imperial majesty the Emperor Frederick Barbarossa, study at the university of Paris, the third crusade up to the death of the emperor, the acquisition of the mummified bodies of the three kings for Cologne Cathedral, the discovery of the Holy Grail, the writing of a letter from Prester John and a journey to the fringes of the Empire of Prester John himself and an escape from the fortress of the Old Man of the Mountains...That is unless it was all a hashish inspired dream...Or a lie from beginning to end.

In a recent episode of In Our Time one of the speakers suggested that Bernard Hamilton first came up with the idea that the court of Barbarossa came up with the first letter from Prester John, the question for me now is did Hamilton publish before Eco or Eco before Hamilton. Is this novel about a liar as close to the truth of the invention of a medieval myth as we can get? :)