Bernal Diaz' detailed eyewitness account of the conquest of Mexico by Cortez and his conquistadors in the early 15th Century is fascinating as it is the only eyewitness account of what Aztec civilization was like before the Spanish changed it. Bernal wrote it when he was in his 80s and didn't care about who he was ticking off, and in fact most of the guys had died already anyhow. He lived in Moctezuma's palace for several months and describes in detail Aztec court ritual, etiquette, customs and so forth. It's an amazing book.