The castle of Antimachia is located in the center of the island of Kos, southeast of the village of Antimachia. It is a remarkable medieval fortress. According to written testaments of the 14th century, the castle also served as a prison for condemmned knights.
The castle is build along a hill with a view to the southern coast of Kos. It has a triangular shape with a peak to the east. Every side of the castle is organized as an independent fortification line that follows the shape of the terrain.
At the entrance there is a massive crescent shaped bastion with deep ramparts. The castle was renovated by the Knights Templar in 1494 after a destructive earthquake. The existing walls were reinforced and new battlements of various types were added along the external wall.
Inside the castle, one still finds ruins of the old settlement of Antimachia, many cisterns and two churches. The settlement was abondened in 1840.