The Tersane was built near the Kızılkule on the commission of Sultan Alaaddin Keykubat in 1227. The site was chosen to maximise the use of daylight, and the dockyard consists of five bays, each covered by a pointed barrel vault, and connection passages spanned by pointed archest The entrance portal bears an inscription adorned with rosettes of the arms of Sultan Alaaddin Keykubat.

This was the first dockyard built by the Seljuk Sultanate in the Mediterranean, and for this reason it is of immense importance. When Sultan Alaaddin Keykubat completed both the Alanya Dockyard and the Shop Dockyard on the Black Sea coast, he was glorified as “the Sultan of two seas”. The dockyard has a masjid as well as a guard room and a water well which is no longer in use. The Tersane can be reached by boat or by walking over the walls from the Kızılkule