The ancient rivalry between Tegea and Mantineia…

The ancient rivalry between Tegea and Mantineia has led Epaminondas to encourage the Arcadians to establish the fortified city of Megalopolis (the name means “large city,” or “great city”), thirty-six miles (fifty-eight kilometers) southwest of Argos, as the federal capital of the Arcadian League and as a bastion for the southern Arcadians' containment of Sparta.

A confederation of twelve small cities in the northern Peloponnesus and southeastern Thessaly, the league forms initially as a defense against piratical raids from across the Corinthian Gulf.

The new city, spreading extensively on both banks of the Helisson (Elísson) River just above its junction with the Alpheus (Alfiós), is populated by the wholesale transfer of inhabitants from forty local villages and by contingents from Tegéa, Mantineia, and other locations.

Encompassed by strong walls, the city reaches about five and a half miles (nine kilometers) in circumference; its territory, extending twenty-four miles (thirty-nine kilometers) northward, is the greatest of any city-state in Arcadia.