Samarra

Samarra, on the Tigris north of Baghdad in Iraq, was founded in 836 by the Abbasid caliph al-Mu'tasim as a new imperial capital to house the Turkish army, and served as the caliphal seat until 892. It is significant in Twelver Shi'ism as the residence and burial place of the imams Ali al-Hadi (d. 868) and Hasan al-Askari (d. 874).