Eretria (Greek: literally "city of the rowers") is a town in Euboea, Greece, facing the coast of Attica across the narrow South Euboean Gulf.

It is an important Greek polis in the 6th/5th century BCE, mentioned by many famous writers and actively involved in significant historical events.

Excavations of the ancient city began in the 1890s and have been conducted since 1964 by the Greek Archaeological Service (11th Ephorate of Antiquities) and the Swiss School of Archaeology in Greece.