The ceremonial enclosure of Khasekhemwy–Hierakonpolis’ only standing monument is built entirely of sun-dried mud brick, with walls 5 meters (16.4 feet) thick and still preserved in places to its original imposing height of 9 meters (29.5 feet). It is the oldest freestanding mud-brick structure in the world. For the third time, it has been listed with the World Monument Fund as one of the world’s 100 most endangered monuments. Decorated on its exterior with a pattern of recessed paneling or niches and originally plastered white, it must have been a striking sight in its time. Almost 5,000 years later, it stands as a testament to the abilities of its builder, King Khasekhemwy, the last ruler of the Second Dynasty (ca. 2686 B.C.), but the reasons for which it was built remain a mystery.