Although it is not certain when Marmaris was founded, in the 6th century BC the site was known as Physkos and considered part of Caria.
According to the historian Herodotus, there had been a castle on the site since 3000 BC. During the Hellenistic Age, Caria was invaded by Alexander the Great and the castle was besieged. The 600 inhabitants of the town realised that they had no chance against the invading army and burned their valuables in the castle before escaping to the hills with their women and children. The invaders, well aware of the strategic value of the castle, repaired the destroyed sections to house a few hundred soldiers before the main army returned home.
The next important event during the history of Marmaris was almost two thousand years later, in the mid-fifteenth century, when the Ottoman Empire began to rise after the efforts of Sultan Mehmed the Conqueror, who succeeded in conquering and uniting under one banner the various tribes and kingdoms of Anatolia and the Balkans, together with Constantinople. Some of his greatest difficulties came from the Knights of St. John, who occupied the Dodecanese Islands. Based in Rhodes, the Knights had fought for many years; they were able to withstand the onslaughts of Mehmed II until a succeeding and more powerful Sultan came on the scene.
Marmaris Castle was rebuilt from scratch in 1522 by the Ottoman sultan Suleiman the Magnificent when he had set out for his campaign on Rhodes, during which Marmaris served as a base for theOttoman Navy.
Lord Nelson and his entire fleet sheltered in the harbour of Marmaris in 1798, en route to Egypt to defeat Napoleon's armada during the Mediterranean campaign.
Since 1979, renovation work has been continuing at the castle, in order to restore it back to its original condition. Under the auspices of the Ministry of Culture, the castle was converted into a museum. There are seven galleries, of which the largest is being used as an exhibition hall and the courtyard is decorated with seasonal flowers. Built at the same time as the castle in the bazaar, there is also a small Ottoman caravanserai built by Suleiman's mother Ayşe Hafsa Sultan.