Panagia Drosiani Naxos

Located 2.5km north of Halki, just below Moni, this is among the oldest and most revered churches in Greece. Inside are several small, cavelike chapels. In their depths, monks and nuns secretly taught Greek language and religion to local children during the Turkish occupation. Several frescoes still grace the walls, dating from the 7th century. Look for the depiction of Mary in the eastern chapter; the clarity and expression is incredible.