Qal'a al-Marqab, from the Arabic word for "watch tower" is a castle located on a hilltop just southeast of Baniyas on the Syrian coast. The site overlooks the coastline and also affords views eastward over the hilly regions west of Hims and Hama. The fortifications were first built during the early Islamic period as a defense against Byzantine expansion. During the twelfth century, the castle fell into the hands of the Crusaders and became a seat of the Hospitallers. Qal'a al-Marqab returned to Muslim control during the Mamluk period when in 1285 AD/682 AH a successful siege led by Sultan Qalawun, after which it served as a state prison.
The castle sits on a triangular walled enclosure following the contour of the mountaintop. The castle itself sits at the southern tip of this enclosure behind a second defensive wall, while the northern part of the enclosure served as an open area used for farming and raising livestock. The castle itself in the southern portion of the site contained a chapel constructed in 1186, a donjon, a main hall and two other halls. A cistern outside the perimeter walls supplied water for the castle's inhabitants.
Elisséeff, N. "al-Marḳab." In Encyclopaedia of Islam, Second Edition. Edited by P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Accessed May 9, 2017. http://dx.doi.org/10.1163/1573-3912_islam_COM_0687.