Qasr Marid () is a castle in Dumat Al-Jandal - in the north of Saudi Arabia built before AD 272. Its walls are 80 cm - 1 meter (2'8"-3'3") thick. The castle commanded the old city of Adumato. Excavations made by Khaleel Ibrahim al-Muaikel in 1986 added to observations made in 1976 that a homogeneus layer of Roman-Nabataean pottery sherds indicated a prosperous community during the time of the Nabataeans to whoms realm the region probably belonged. In 633 CE, Khalid ibn al-Walid captured Dumat Al-Jandal and it became a part of the newly formed Islamic empire.