Kos Castle

Kos Castle showing heritage architecture
Kos Castle
Kos Castle featuring building ruins
Kos Castle
Kos Castle showing a ruin


Enjoy wonderful views of the Aegean Sea from the ruins of this massive stone castle, which dates back to the 14th century.

Wander through the ruins of Kos Castle, a magnificent 14th-century fortress at the entrance of Kos Harbour. The mediaeval fortification was built by the Knights of Saint John to defend the island from the Ottomans. 

The knights were a Christian military order who occupied Kos for about 200 years, until they were driven out by the Turks in the early part of the 16th century.

To get to the castle, which is also known as Nerantzia Castle, go over the old stone bridge. It used to connect the fortified complex to mainland Kos, because the site was once an island. Then spend about an hour touring the remains. The building was constructed with local stone as well as materials from earlier structures. See examples of this at the main gate. Above the entrance is a frieze and masks from the Hellenistic period. There are also basalt columns that are believed to have come from an early Christian basilica.

Go to the oldest part of the castle, the inner fortified wall, which has four towers at its corners. A deep moat and drawbridge separate it from the outer section. Look for blazons on some of the masonry. These are coats of arms of the Grand Masters of the Knights of Saint John. Note the thickness of the outer walls, which were designed to protect against heavy artillery fire. 

Walk on ramparts, climb up old stone staircases and see the remains of rooms and passageways. Take care when walking, because the ground is uneven in places.

Learn more about the history of the castle and of the knights by visiting the museum. The building is located between the castle’s two sections and was once a warehouse. Browse its collection, which includes sculptures and altars.

Kos Castle is situated in the harbour area and is open every day except Monday, and there is a modest fee for admission. In addition to studying the ancient remains, enjoy the fabulous views of the Aegean Sea from the ramparts.

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