The castle of Kalamata is located in the northwestern part of the town on a low rocky hill above the river Nedos. Its construction dates back to the Byzantine period, but its current form is based on the reconstruction in the early 13th century by the Franc prince and founder of the Achaia, Geoffrey I of Villehardouin.
In typical form of Byzantine castle, located at the steepest point of the hill is a tower-domed water reservoir, where church relics have been identified. The inner fortification wall surrounds the top of the hill, while the wider wall protects a larger area, on the eastern part of the castle.
Modifications on the castle of Kalamata were made by the Venetians during the second period of Venetian occupation, specifically during 1685-1715. The gate reconstructions on the eastern side are indicative of this as is the relief of Leon of Saint Mark above the entrance door.
During the 18th century the castle of Kalamata loses its strategic importance, while in the early 19th century sees its abandonment. In 1825 the army of Ibrahim destroy it significantly.