The Abbasid architecture of the Abbasid Caliphate (750–1513) was strongly influenced by Sassanid architecture, and later by Central Asian styles. The Abbasid mosques all followed the courtyard plan. The earliest was the mosque that al-Mansur built in Baghdad. since destroyed. The Great Mosque of Samarra built by al-Mutawakkil was . A flat wooden roof was supported by columns. The mosque was decorated with marble panels and glass mosaics. The prayer hall of the Abu Dulaf mosque at Samarra had arcades on rectangular brick piers running at right angles to the qibla wall. Both of the Samarra mosques have spiral minarets, the only examples in Iraq. A mosque at Balkh in what is now Afghanistan was about square, with three rows of three square bays, supporting nine vaulted domes.