Raqqa and al-Rāfiqah merged into one urban complex, together larger than the former Umayyad capital, Damascus. In 796, the caliph Harun al-Rashid chose Raqqa/al-Rafiqah as his imperial residence. For about 13 years, Raqqa was the capital of the Abbasid Caliphate, which stretched from Northern Africa to Central Asia, but the main administrative body remained in Baghdad. The palace area of Raqqa covered an area of about  north of the twin cities. One of the founding fathers of the Hanafi school of law, Muḥammad ash-Shaibānī, was chief qadi (judge) in Raqqa. The splendour of the court in Raqqa is documented in several poems, collected by Abu al-Faraj al-Isfahāni in his "Book of Songs" (''Kitāb al-Aghāni''). Only the small, restored so-called Eastern Palace at the fringes of the palace district gives an impression of Abbasid architecture. Some of the palace complexes dating to the period have been excavated by a German team on behalf of the Director General of Antiquities. There was also a thriving industrial complex located between the twin cities. Both German and English teams have excavated parts of the industrial complex, revealing comprehensive evidence for pottery and glass production. Apart from large dumps of debris, the evidence consisted of pottery and glass workshops, containing the remains of pottery kilns and glass furnaces.