Known. A tall mud-brick tower still stands at Kerma.
Kerma is in northern Sudan. The Kingdom of Kerma lasted from about 2500 BC to about 1500 BC. Its capital was one of the earliest towns in Africa outside Egypt. The best-preserved tower is called the western deffufa. Its walls are mud brick, which helps keep the inside cool in the heat. It is 18 metres high and covers about 1,400 square metres. It has three storeys, with rooms and passages. Paintings on the inside walls are still there, and a shrine was found on the roof.
People are still not sure what the western deffufa was for, though it almost certainly belonged to the religious life of Kerma.
https://www.ancient-origins.net/ancient-places-africa/kerma-sudan-006597