Gaziantep Castle is a castle located in Gaziantep, Turkey. It was first built by the Hittite Empire as an observation point and later built into a main castle by the Roman Empire on top of a hill in the center of Gaziantep in 2nd and 3rd century AD. The castle underwent further expansion and renovation under the Byzantine emperor Justinianus between 527 and 565 AD. Gaziantep Castle has been renovated numerous times and took its final shape.