Undoubtedly one of the most significant palaeochristian churches in Greece, the church of Ekatontapiliani (Church of 100 Doors) is reputed to be built in part by emperor and saint Constantine, in fulfilment of a wish to his mother Saint Eleni (Saint Helen). Constantine built the three-aisled basilica in the 4th century AD, with additions and changes in the 6th century AD.
It is now an amalgam of palaeochristina, Byzantine, post-Byzantine and Cycladic architecture, with parts of the marble from even earlier Greek epochs. The church comprises the temple of Holy Mary, the basilica of St. Nicolas, the chaple of St. Dimitrios and the temple of St. Tehodosia. Christenings for adults took place until the 4th century, supplanted by christenings for infants until today. The inside with its marble and sculpted decor, iconostases and icons is also interesting to inspect.