From the Homeric times and antiquity, it was one of the most important city-states of the ancient Greek world (6th-5th century BC). The city during the classical era was founded most probably during the 9th century BC, as the port of Lefkantium, 15 km to the west.

In the years of the 1821 Greek Revolution, after the destruction of Psara (June 1824), a town was founded on the site of the ancient city, initially under the name Nea Psara, but then it was renamed Eretria.

Today Eretria is a vibrant seaside tourist resort, with upgraded facilities of luxury hotels & spa. The footprints of its history are easily found North of the port, where the ancient acropolis lies, on a limestone hill 123 meters high. Numerous valuable findings of ancient times came to light during the excavations carried out since the 19th century, so as the Ancient Theatre of Eretria. The archaeological findings are housed – along with others from the wider area – in the Archaeological Museum of Eretria. An important monument of Antiquity that is preserved and worth visiting is the «House of the Mosaics», where one can admire the mosaics of a particular style.