Ancient Eretria is in Euboea(Evia).

Eretria was an important city-state of antiquity that flourished for several centuries and acquired colonies, but after the victory of Philip of Macedonia over the Greeks, it was gradually led to decline and it was finally depopulated during the first century B.C.

In the ancient city a new town was founded in 1824 by the residents of Psara island, who were forced to abandon their homes. In fact, the site was originally named Nea Psara, only to switch later to its older name. Today among the buildings of modern Eretria, one can still catch a glimpse of the remains of the ancient city, including:

• The Temple of Apollo: the religious center of the ancient city from which only the foundations are preserved
• The Ancient Theatre of Eretria, built on an artificial hill, with a probable capacity that fit over six thousand spectators
• The Temple of Isis
• The Eretria Dome, part of the town's ancient market, from which the foundations are preserved.
• The Macedonian Tomb
• The House of Mosaics, constructed around 370 BC featuring floor with impressive decorations.

Many of the mobile findings of the above archaeological sites can be seen in the Archaeological Museum of Eretria. Once you find yourself in Eretria, take the opportunity to admire the remains of the ancient city.