On a square, this Byzantine church was founded by St Helena, mother of Emperor Constantine (280-337); the current building is largely 10C. The church of Our Lady of the Hundred Doors blends a thee-nave basilica plan with a Greek cross plan. Note the gynacaea, 17C stone iconostasis and Byzantine ciborium with four classical columns. To the right of the church, the chapel of St Nicholas has a 6C font. A small Byzantine museum (to the left on exiting the church) has icons and devotional objects.