Pliny 
Letters of Pliny 

Classic collection of letters. According to Wikipedia: 'Gaius Plinius Caecilius Secundus, born Gaius Caecilius or Gaius Caecilius Cilo (61 AD – ca. 112 AD), better known as Pliny the Younger, was a lawyer, author, and magistrate of Ancient Rome. Pliny’s uncle, Pliny the Elder, helped raise and educated him. They were both witnesses to the eruption of Vesuvius on 24 August 79 AD. Pliny is known for his hundreds of surviving letters, which are an invaluable historical source for the time period. Many are addressed to reigning emperors or to notables such as the historian, Tacitus. Pliny himself was a notable figure, serving as an imperial magistrate under Trajan (reigned AD 98–117).’