Castle of Sifnos

Kastro was the capital of Sifnos until the 19th century, a fortified village on a rocky hill above the east coast. Its outer houses form a continuous wall facing the sea, and inside is a tight maze of whitewashed lanes, arched passages, small churches and marble fragments reused from ancient buildings, set into walls and doorways.

People still live here, which is what keeps it from feeling like an open-air museum. There is a small archaeological museum inside the walls; check its hours before you go. Leave the car at the entrance, as the lanes are for walking only, and wear shoes with grip on the polished stone. Go in the late afternoon, then walk down to the chapel of the Seven Martyrs on the rocks below and stay for dinner in one of the village tavernas.