Kastro is the main and most popular sight of Sifnos
island, not only because the emblematic Church of Seven Martyrs (Efta Martyres) is there, but also because the village is a representative of one of the most charming kastros (castles) of the Cyclades. In short, it is a must during your visit to Sifnos.
Kastro is located on the east coast of the island, 2 km away from Apollonia
. It is built on a hill above the sea, and of course, you can access it only on foot - all vehicles must be left at the parking space before the entrance, right after the windmills. The village is a labyrinth of tiny white alleys, arches between the tightly built houses, miniature squares and churches. Here and there you can see parts of the solid walls beneath or between the houses, and some of the gates which used to protect the settlement from pirates in the past. The central alley passes through the middle of the castle and then naturally turns toward the sea, intersected by many passages at various places, so you can easily lose a few hours exploring them. The sea view is breathtaking and from this area of Kastro you can see the church of the Seven Martyrs and the steps which lead down to it. Inside the village there are a few cafe-restaurants, two small shops and hotels, but in general it lacks the lively atmosphere of the rest villages and sometimes you can even happen to meet nobody during your walk.
In a small cove below the hill of Kastro lies its harbor, called Seralia
. It consists of a few fish tavernas and a rocky beach with transparent water.