Inside the donjon, in the chapel on the lower floor. It is 10 x 24 meters. Two arches split the vault in three. The apse is flanked by two sacristies. There are five firing slits in the 3 meters thick walls that serve as windows. The height is almost 18 meters. To the right is a staircase to a higher floor.

What we see now probably dates from reconstructive work after an earlier version, dating from around 1112, had been demolished by Nur al-Din during campaigns in 1167 and 1171. That work was executed about 1188, then an earthquake necessitated further improvement, so roughly the current donjon is from the 13th century. It fell into Muslim hands in 1271 when Sultan Baybars took it, when on his way to Krak des Chevaliers.