|Population statistics (as of 2001)|
|- Area:||205.393 km2 (79 sq mi)|
|- Density:||17 /km2 (44 /sq mi)|
|Time zone:||EET/EEST (UTC+2/3)|
|Elevation (center):||600 m (1,969 ft)|
|Postal code:||220 05|
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. 778 in 2001). It is located in the northeastern part of Arcadia. The municipal unit has a land area of 205.393 km² and a population of 3,510 inhabitants. Its largest other towns are Artemísio (pop. 654), Loukás (653), and Kapsas (505).
Poseidon was the patron god of Mantinea.
The First Battle of Mantinea, in 418 BC, was 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 Laches the Athenian commander 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 Peloponnesian War. Later, Sparta used the Peace of Antalcidas as a pretext to break Mantineia into its constituent villages. In response, the Mantineans expelled pro-Spartans from the city. After the Spartan defeat at the end of the Corinthian War, Mantineia reformed into a single city.
The Second Battle of Mantinea, in 362 BC, led to the fall of Theban hegemony. In that battle, Athens and Sparta were allied. Thebes won the battle, but its greatest general, Epaminondas, was killed in the fighting.
Modern-day Mantineia is the region around the city of Tripoli in Arcadia, and was named after the namesake city of old. It is also the name of a Protected designation of origin of Greek blanc de gris wine, made of the moschofilero grape traditionally grown in the region. The seat of Mantineia is Nestani, home to about one-fifth (20%) of the population.
Mountains surround the valley, including the Lyrkeia mountains as well as the Mainalo mountains to the southwest. The valley consists of vineyards, potato and wheat farms as well as other crops, and covers about half of the municipality. Several floods ravaged Mantineia in the mid-20th century, even to the extent of forming a lake that has since been drained. Forests dominate the mountains. Rocks and grasslands cover most of the northeast.
The Mantineia Marble, dated to the 4th century BC and now exhibited at National Archaeological Museum of Athens depicts the mythical contest between Apollo and Marsyas, with a Greek Pandouris being played by a muse seated on a rock. This is important to researchers into the history of musical instruments  Lutes have been present in ancient Greece 
The municipal unit Mantineia is subdivided into the following communities (constituent villages in brackets):
- Artemisio (pop: 654)
- Kapsas (pop: 505)
- Loukas (pop: 726, Loukas, Milia)
- Nestani (pop: 1020, Nestani, Milea, Gorgoepikoos Monastery)
- Pikernis (pop: 192)
- Sagkas (pop: 241)
- Simiades (pop: 172, Simiades, Neos Kardaras)
The province of Mantineia (Greek: Επαρχία Μαντινείας) was one of the provinces of the Arcadia Prefecture. Its territory corresponded with that of the current municipality Tripoli. Its seat was the town Tripoli. It was abolished in 2006.
- Ancient Mantineia (Greek)