The ruins of a stone and mud-brick fort overlook the Dal Cataract of the Nile River in northern Sudan. This cataract (waterfall) of the river is located in the Nubia region, which was once part of the ancient kingdom of Kush. Ancient and medieval ruins lie along the Nile in this region, although many ruins were submerged under Lake Nasser after the Aswān High Dam was built in the 1960s.