The Castell de Forna (Adsubia) is is the best preserved and most accessible of the Marina Alta castles.
The building is quadrangular, with a square tower at each corner, but it is slightly asymmetric with the northeast tower being larger with a water cistern and a room covered by a cross vault. Judging from the remains, this larger tower was originally a military or refuge watchtower (atalaya) during Almohad Islamic times (12th - 13th centuries). The village of Forna was taken by King Jaume I from the Muslims in 1258, but the first record of the castle was not until the middle of the 14th century and its extension and conversion into the feudal residential palace we see today seems to have occurred in the middle of the 15th century when the village was owned by the Cruilles family. The castle was excavated in 1981, revealing ceramics from the 14th to 16th centuries. In 2003 it was extensively restored by the Adsubia/Forna Town Hall with technical assistance from the MARQ. (Provincial Archaeological Museum of Alicante)Of particular note is a set of late medieval / renaissance graffiti drawings on the wall of a room in the northwest tower. This is one of the best sets of such drawings in Alicante province.