Lives of the Twelve Caesars by Suetonius
An account which covers the Roman rulers from Julius Caesar to Domitian, and remains one of the richest and most and fascinating of all Latin histories. Suetonius gathered much of his information from eye-witnesses, checking his facts carefully and quoting conflicting evidence without bias. But his history is also the most vivid and the raciest account we have of scandalous and amusing incidents in the domestic lives of the first Caesars.