The ruins of Heraqlah are situated eight km west of al-Raqqa. Heraqlah was originally founded as a Roman military camp settlement, but was later developed by Abbasid Caliph Haroun al-Rashid into a monument celebrating his triumph over Byzantine forces. The terraced monument is enclosed by a circular stonewall about 500 meters in diameter. The structure is 103 square meters with four towers, one at each corner and an iwan that opens to the intermediate space between the terrace and the circular wall. Four gates on the outer wall open up to the exterior and mark the key directions (north, south, east and west).
Source:
Burns, Ross. Monuments of Syria, 201. London: I.B. Tauris & Co Ltd., 1992.
Rihawi, Abdul Qader. Arabic Islamic Architecture in Syria, 87-88. Damascus: Ministry of Culture and National Heritage, 1979.