A small Portuguese fort that dates back to the 16th C, it has been rebuilt many times since then. Abu Mahir, built upon a rock island, could accommodate only about 100 men and was primarily a signal tower from which to observe the approaching ships. Only the southwest tower, part of another tower and two storerooms survive, as well as four cannons. Abu Mahir is still used as a Bahraini coast guard station. Land reclamation work has made it part of Bahrain’s Muharraq coastline. It is considered the sister fort of Qal’at Arad.