The Early Christian Basilica of Olous (built in 4-5th century) is located at position Poros and was excavated in 1937 and 1960. This is a brilliant sample of religious architecture of its time and it is considered to have been the cathedral of the ancient town Olous, which is today submerged in the lagoon of Elounda.
Olous was probably the base of the local Diocese, as several more basilicas have been identified nearby. The mosaic floor of the basilica is one of the finest surviving samples in Crete with geometric templates, representations of dolphins and peacocks, and inscriptions of donors.
A very important finding is the sign of alliance agreement between Olous and Rhodes, and a Roman inscription, both exhibited at the Archaeological Museum of Agios Nikolaos.