One of the most interesting monuments of ancient Eretria is Iseion, a temple dedicated to Isis and other Egyptian deities. It is located in the southern part of the city, behind the small port to connect the mosque with various merchants who had interests in Eretria.
The church must have been built in the 4th century. B.C. and was framed by various other buildings and auxiliary spaces. The worship of Isis and the Egyptian deities was introduced into the Greek area during the Hellenistic period (by Greek merchants who came from Egypt after the unification of the territories by Alexander the Great). Their worship in Eretria has also been recorded epigraphically.
The temple of Isis was initially simple, facing east, with a treadmill with representations. Inside it was an adorable statue of the goddess, which was made of clay and in front of the temple was the altar. The temple was rebuilt after 198 BC, when the city was destroyed by the Romans. It then acquired a larger and better founded outer trait and was framed by open galleries. To the north of the temple there were a further fifteen, in total, buildings and auxiliary spaces, characterized by excavators as clearing sites. Between them there was a courtyard and a men's room, while one room of the complex had an impressive mosaic floor, decorated with rhombuses.
The mosque of Isis and the other Egyptian deities was excavated in 1917 by I. Papadakis. In recent years, the Archaeological Service of the Ministry of Culture has made new excavations in the area of the temple, which have revealed another complex with courtyards and rooms, directly related to the sanctuary.