Pyrgos Castle is the ruined Venetian stronghold above Pyrgos, built when Santorini needed hilltop defenses against raids. The remains are woven into the village lanes, with old walls, narrow passages, churches, and views across the island and caldera.
It is best visited as part of a slow walk through Pyrgos rather than as a stand-alone museum stop. Come in the morning or near sunset, when the light and views are at their best.