City in northern Syria on the Euphrates River, founded by the 'Abbasid caliph al-Mansur and reputedly modeled on those of Baghdad. Raqqa is on the site of an ancient Greek city, Nicephorium, and a later Roman fortress and market town, Callinicus. It flourished again in early Arab times when the 'Abbasid caliph Harun ar-Rashid built several palatial residences there and made it his headquarters against the Byzantines. The surviving part of the Baghdad gate shows that it had a four-centered arch surmounted by a band of three-lobed niches resting on engaged colonnettes. The congregational mosque, also attributed to al-Mansur, was a rectangular building with a sanctuary of three arcades. Raqqa ware is 12th- and 13th- century earthenware with painted ornament under thick alkaline glaze.