Oia Castle, Santorini (must see)

Oia Castle, often identified as the Castle of Saint Nicholas, is a late-15th-century fortified site and one of the best-known historical landmarks in Oia today. Its ruins remain a major gathering point, especially in the evening, because the exposed cliffside position offers wide caldera views.

The castle was developed during the period of Venetian domination as part of Santorini’s network of fortified settlements, created to guard against pirate raids in the Aegean. Raids could involve theft and the taking of captives, which helps explain why local settlement patterns favored compact building and rapid retreat to defensible points. Some accounts also describe residents hiding valuables in pits beneath buildings within the fortified area; this is often repeated in local narratives about the site.

Within the castle complex, there were residences associated with the Venetian rulers, and the high position functioned as a lookout over sea routes. The stronghold is often said to have been taken by Ottoman forces in 1577, while wider histories place the Ottoman conquest of Santorini within the broader annexation of the Cyclades in 1579, so it’s best understood as a late-16th-century transition from Venetian to Ottoman control.

The site was severely damaged in the 1956 earthquake, when large sections of the fortifications and parts of the surrounding settlement collapsed down the cliffs. What remains today are fragments of walls and the base of defensive elements, but the viewpoint is still exceptional. From the ruins, visitors can clearly see the volcanic islets of Nea Kameni and Palea Kameni in the center of the caldera, as well as the nearby island of Thirasia to the northwest.