Qasr al-Hayr al-Gharbi is a Syrian desert castle or qasr located 80 km south-west of Palmyra on the Damascus road. The castle is a twin palace of Qasr al-Hayr al-Sharqi, built by the Umayyad caliph Hisham ibn Abd al-Malik in 727 CE. It was built in the Umayyad architectural style.