The Panagia Ekatontapyliani, which dates from AD 326, is one of the finest churches in the Cyclades. The building is three distinct churches: Agios Nikolaos, the largest, with superb columns of Parian marble and a carved iconostasis in the east of the compound; the ornate Church of Our Lady; and the ancient Baptistery.

The name translates as Our Lady of the Hundred Doors, though this is a wishful rounding-up of a still-impressive number of doorways. The Byzantine Museum, within the compound, has a collection of icons and other artefacts.