Al-Mutawakkil (r. 847–861) aggressively pursued new construction, extending the central city to the east and building the Great Mosque of Samarra, the cantonment of Balkuwara and numerous palaces. After moving to Damascus in 858, he returned to Iraq and undertook his most ambitious project, the new city of al-Mutawakkiliyya to the north of Samarra. Included in the new area was the palace of al-Ja'fari (Ja'far being his given name), which he moved into in 860. In the following year, however, he was assassinated, and al-Mutawakkiliyya was abandoned soon after.