This Fatimid fortress at Ajdabiyah is outside the walls of ancient Ajdabiyah, 500 meters to the north between the city and the Mediterranean. The exterior walls of the defensive palace measure 33.5 meters x 22.5 meters with round towers at each corner and rectangular towers at the middle of the walls. The walls are built of local limestone joined with lime mortar and filled with a rubble core.
The entrance on the northeast wall leads to a vestibule. The vestibule opens onto a large central courtyard with a well surrounded by the rooms of the qasr. At the southwestern end of the courtyard, through another vestibule, are three vaulted rooms, the remains of which are still standing. The central room boasts a barrel vault capped by a squinch-supported dome. This room was most likely the audience hall of the palace patron, while the two side rooms may have been private accommodations. The more public rooms abutting the courtyard probably served and housed troops.