Rhaba

Al-Rahba (/ALA-LC: al-Raḥba, sometimes spelled Raḥabah), also known as Qal'at al-Rahba (قلعة الرحبة), which translates as the "Citadel of al-Rahba", is a medieval Arab fortress on the west bank of the Euphrates River, adjacent to the city of Mayadin in Syria. Situated atop a mound with an elevation of 244 meters (801 ft), al-Rahba oversees the Syrian Desert steppe. It has been described as "a fortress within a fortress"; it consists of an inner keep measuring 60 by 30 meters (197 ft × 98 ft), protected by an enclosure measuring 270 by 95 meters (886 ft × 312 ft). Al-Rahba is largely in ruins today as a result of wind erosion.

The original site, which was known as "Rahbat Malik ibn Tawk" after its Abbasid namesake and founder, was located along the Euphrates. It was viewed by Muslim armies, caravans and travelers as the key to Syria from Iraq and sometimes vice versa. Bedouin tribes often took control of it and used it as a launching point for invasions of northern Syria. Because of its strategic location, al-Rahba was frequently fought over by Muslim powers, including local lords, the Hamdanids, the Uqaylids, the Mirdasids and the Seljuks, among others. Rahbat Malik ibn Tawk was destroyed in an earthquake in 1157.