The fortress was built in 3000 BC. Ionians, then Marmaris was still called Fiskos. According to historians, it was with the construction of a fortress in the center of the peninsula on a hill, from where an overview of the bay is possible, that the development of the ancient city of Fiskos began. The fortress was often rebuilt. The last reconstruction of the fortress was carried out in 1522 under the leadership of Sultan Suleiman the Magnificent after his successful occupation of Rhodes. The main decorations of the fortress were the tower, powerful battlements and cannons that guarded the bay and the city. Some of the cannons have survived to this day.
Trying to recreate the former grandeur of the fortress as much as possible, restoration work began in 1979. By decision of the Ministry of Culture, the fortress was converted into a museum. The inner courtyard has been turned into a garden, which is decorated with bright flowers and ancient inscriptions with sculptures. There are fragments of marble bas-reliefs near the entrance. Most of the 7 galleries of the museum are used as exhibition halls for artists and sculptors in Turkey. In addition to regular exhibitions, the museum-fortress often hosts cultural and artistic events. Here they conduct lessons on the history of the region for schoolchildren.