The “Lower Castle” used to be one of the most important castles in the Aegean. Today, it is ruined, although it remains one of the touristic attractions of Andros.
The Lower Castle was built on a small peninsula and on an islet at the eastern part of the island of Andros, where Chora is located today. The site offered natural protection being surrounded on three sides by water with only the western one facing the mainland.
The name of the castle in Greek is "Kato Kastro" which means Lower Castle to distinguish from the other major castle of Andros, the Upper Castle or Castle of Faneromeni.
The castle is often mentioned also as "Mesa Kastro" (Inner Castle), a name that usually refers to the part on the mainland only.
After the 4th Crusade and the Fall of Constantinople in 1204, the Latins turned to other parts of the Byzantine empire. Andros was captured by the Venetians in 1207. Their leader was Marino Dandolo, a nephew of The Doge of Venice, Enrico Dandolo, one of the heads of the 4th Crusade.
The Venetians built three major castles in Andros: the Lower Castle (the modern Chora), the Upper Castle (also known as Phaneromeni) and the fort of Makrotantalo (or Ostodosia). The first two were fortified settlements, while the third was a simple outpost, probably manned by a small garrison.
The Lower Castle was built by Marino Dandolo almost immediately after the capture of the island. He started by building his mansion on the little island at the tip of the peninsula.
The castle was in very good condition until World War II. Then in 1943, the Germans bombed the port of Andros and the castle was almost completely destroyed.
The settlement was surrounded by a single curtain-wall, formed by the back walls of the inhabitant’s houses. What remains nowadays from this wall is a small part of the curtain founded on bedrock. The construction of the settlement’s enclosure is typical for the Aegean islands during the Frankish period, especially for those belonging to the Venetians of the Ducat of Archipelagos (such as Sifnos, Antiparos, Kimolos).