Château des Chevaliers de Saint-Jean

Kos, Greece

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The Château des Chevaliers de Saint-Jean, also known as the Castle of the Knights or Neratzia Castle, is a prominent medieval fortress located at the entrance of Kos harbor in Greece. Built mainly between 1436 and 1514 by the Knights Hospitaller (Knights of Saint John), it served as a key defensive stronghold to protect Kos from Ottoman attacks and guard important sea routes in the Aegean.

The castle incorporates architectural elements from the ancient city of Kos and the nearby Asklepieion sanctuary, such as columns and architraves. It consists of two fortified enclosures with circular towers, bastions, battlements, and gun ports, showcasing classic knightly fortification design.

During the Knights' rule from the early 14th century until 1523, the castle safeguarded the harbor and local population, playing a crucial role in resisting numerous Ottoman sieges until the island fell to Ottoman control. The Knights then relocated to Malta, but their legacy remains visible in the castle’s imposing structure as a historical symbol of Kos’s strategic importance in medieval naval defense.