Built south of the rapids of the Second Cataract, the Upper Fortress of Mirgissa/Iqen protected this site on Egypt's southern frontier and controlled river and desert roads. It was linked to the enclosure walls surrounding the settlements, the workshops and the harbour in the lower parts of the site. It was probably built under the reign of Senwosret I, as was the fortress Buhen further north. It is a good example of Middle Kingdom's military architecture with its double fortified enclosure, ditches and glacis. It also houses the governor's residence, the armory, buildings assigned to major Egyptian institutions, sanctuaries, workshops, and various habitats. Four main levels have been discovered. During the twelfth dynasty, the first enclosure wall was replaced by a large fort whose interior map did not vary much; it was accessed through a monumental gate. At the end of the Middle Kingdom, the settlements diversified, with the construction of residences of various sizes. During the New Kingdom, the site lost its primary function and the buildings were divided or rebuilt. The furniture unearthed is varied, including a remarkable collection of lithic weapons from the Middle Kingdom; the hundreds of ceramics have made it possible to establish a new typology.