Byzantine era (330-1207). The advent of Christianity in the fourth century leads to the construction of many churches over ancient temples. Today, there are more than 500 churches on the island. Panayia Drosiani near Moni and Panayia Protothroni near Halki are two important monuments of the Early Christian period. The fortified monastery of Fotodotis Christos on the outskirts of Danakis also dates from this period. The Byzantines also built castles or fortifications on the island. One example is the Kalogeros Kastro which is built atop a low but inaccessible hill on the island’s northern end. Apano Kastro is located west of the Tragea plain. The Apalirou Castle in the central Naxos is built atop a sheer slope; the island’s Byzantine capital was located at its foothills.
