Mantineia (also Mantinea ˌmæntəˈniːə; Μαντίνεια; also Koine Greek Ἀντιγόνεια Antigoneia) was a city in ancient Arcadia, Greece, which was the site of two significant battles in Classical Greek history.
In modern times it is a former municipality in Arcadia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Tripoli, of which it is a municipal unit. Its seat was the village of Nestani (pop. 486 in 2011). It is located in the northeastern part of Arcadia. The municipal unit has a land area of 205.393 km2 and a population of 2,114 inhabitants. Its largest other towns are Artemisio, Loukas, and Kapsas.
The city emerged from the amalgamation of several neighbouring villages around 500 BC. Its patron god was Poseidon. It was a large city with numerous temples. The fortifications originally were polygonal. The temple of Artemis Hymnia, just on the north of the city, is mentioned by Pausanias. Diotima, who influenced Socrates, supposedly was a priestess there. Near the city was the dam of Mantineia, one of the most advanced examples of ancient technology.
The city was the place of the First Battle of Mantineia, in 418 BC, the largest land battle of the Peloponnesian War. On one side were Sparta and its remaining allies, and on the other were Athens, its allies, plus the cities that had revolted against the Spartans. After the Athenians' commander, Laches, was killed, the battle turned into a rout of the Athenian and allied armies, a result attributed to greater Spartan courage.
Mantineia had been a member of the Peloponnesian League, but during the Peloponnesian War, the city joined Athens. After the war, it was forced to rejoin the Peloponnese. Later, Sparta used the Peace of Antalcidas (387 BC) as a pretext to break Mantineia into its constituent villages. In response, the Mantineans expelled pro-Spartans from the city, but were vanquished in the Siege of Mantinea (385 BC), and the city was dismembered and destroyed. After the Spartan defeat at the end of the Theban–Spartan War, Mantineia re-formed into a single city.