Sifnos is and island of the Cyclades group abounding in monasteries and churches, narrow stone-paved alleys and whitewashed houses. The capital of Sifnos is called Apollonia. The town of Kastro is one of the most beautiful places on the island. It is situated on a small peninsula with a Venetian Castle rising on the top of a hill surrounded at its foot by numerous little whitewashed houses built in the traditional Cycladic style. Visitors enter the town through its Medieval gates. There is so little space that the houses on the slope are built almost on top of each other with some of the roofs actually serving as squares.