The Histories (Greek: Ἱστορίαι Historíai) by Polybius are an account of events in the Mediterranean world from 264 BC to 146 BC, and an attempt to understand Rome's rise to supremacy during that period. His account of Roman institutions in Book VI had a notable influence on later political theorists as an illustration of the benefits of a mixed constitution.
Polybius was a well-placed observer, serving at one time as a military official of the Achaean League. He was later sent to Rome as a hostage and acquired the patronage of Scipio Aemilianus, accompanying him during the final defeat and sack of Carthage.
Free online texts
Gutenberg: The Histories of Polybius, Vol I
Gutenberg: The Histories of Polybius, Vol II
LacusCurtius: The Histories, translated by W.R. Paton. HTML format.
PACE: Histories. Greek text and English translations by W.R. Paton and Evelyn S.Shuckburgh. HTML format.
Wikisource: The Histories, translated by W.R. Paton (1922-27). Multiple formats.
The Great Conversation: Further reading at Tom's Learning Notes
Herodotus: Histories - The extent of Herodotus influence on Polybius is disputed.
Thucydides: History of the Peloponnesian War - Polybius' focus on politics, and his methodology, owes much to Thucydides.
Livy: From the Foundation of the City - uses Polybius as a source.
Josephus: As a Roman client from a conquered nation, Josephus' career has important parallels with that of Polybius.
Ancient Greek resources: Learn to read Greek classics in the original.