Qasr al-Hayr al-Gharbi castle or qasr (Arabic: قصر الحير الغربي), located 80 km south-west of Palmyra on the Damascus road in Syria, 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 Byzantine architectural style.