The Fortress of Al-Ukhaidir or Abbasid palace of Ukhaider is located roughly 50 km south of Karbala, Iraq. It is a large, rectangular fortress erected in 775 AD with a unique defensive style. Constructed by the Abbasid caliph As-Saffah's nephew Isa ibn Musa, Ukhaidir represents Abbasid architectural innovation in the structures of its courtyards, residences and mosque. Excavations at Ukhaidir were conducted in the early 20th century by Gertrude Bell. Ukhaidir was an important stop on regional trade routes, similar to Atshan and Mujdah. The complex comprises a primary hall, a large Iwan, a reception hall and servants quarters.