Which crusader fortress in Jordan was the seat of the Lordship of Oultrejordain?

The crusader fortress in Jordan that served as the seat of the Lordship of Oultrejordain was Kerak Castle.

Kerak, also known as al-Karak, stands on a steep ridge east of the Dead Sea. The Franks developed it into the principal stronghold of Oultrejordain, a strategically important lordship stretching across territory east of the Jordan River. Its position allowed the castle to oversee routes linking Syria, the Dead Sea, Arabia, and Egypt.

Construction of the major castle began in the 12th century under Pagan the Butler, who became lord of Oultrejordain. Kerak’s defences included massive walls, towers, vaulted halls, storage areas, and a deep moat. The fortress was both a military base and an administrative centre, and its lords could threaten caravans travelling between Damascus and Egypt.

Kerak is often confused with Crac des Chevaliers, but that famous fortress was in Syria and was associated with the County of Tripoli and the Knights Hospitaller. Château de Saône was also in Syria, while Mont Saint-Michel was in Normandy. Kerak eventually passed to Muslim rulers and remains a major historic site in Jordan.