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The most prominent structure on the harbor in Kos Town is the Castle of Neratzia, a huge Crusader castle built by the Knights of St. John. The castle was built between the late 1300s and early 1500s. The castle once occupied its own small island.
Admission
Access to the castle is via a bridge. Once across the bridge, you come to the admissions booth. It’s open daily except Tuesdays from 8:30am to 3:30pm, and admission is free (as of October 2023).
Walls
The castle is actually two castles in one. The inner castle is the oldest part of the castle, built in the late 1300s to defend the island against Ottoman Sultan Bayezid I. Only three of the original four towers remain from the old castle, as does the wall facing the sea.
Throughout the early 1500s, the castle was reinforced with outer walls, leaving a huge open space between the new and old walls.
Building Materials
The castle was built using materials from ancient ruins in town and from the Asclepeion. If you pay close attention to the walls during your visit, it’s easy to spot some inscriptions in ancient Greek built into them. There are also tablets with the Coat of Arms of the Knights and an Ottoman prayer niche.
Courtyards
Within the courtyards of the castle, there are several pieces of ancient columns and tombstones scattered about. You’ll also find Ottoman cannons and cannonballs.
