Kastro - the Castle ( Sifnos ) is one of the villages that every visitor should see. The area containing a small castle city of the island has been inhabited since ancient times. The medieval village has been built up on a steep hill and in the same place are the ruins of the ancient Acropolis. The current version of the Castle exemplifies fortress architecture from the Venetian period. The houses are two or three floors and built continuously, so that the outer walls are also the walls of the fortress. Cars are prohibited in Kastro. You can reach the nearby beach via stairs which reveal a small and secluded but beautiful beach with small pebbles.