Who built Great Zimbabwe's giant stone walls without mortar?

Great Zimbabwe is a city of giant stone walls laid without mortar. They were built by the ancestors of the Shona people in the hills of what is now Zimbabwe, and it is the largest stone structure in precolonial Southern Africa.

The city was settled from around 1000 AD, and construction continued from the 11th century to the 15th. The showpiece is the Great Enclosure, whose walls are 11 metres high and dry-stacked, built in the 13th and 14th centuries; it likely served as the royal residence with spaces for rituals. Beside it stand the Hill Complex and the Valley Complex. Scholars disagree on what each one was for. More than 400 sites with monumental mortarless walls are known across Southern Africa; the word Great sets this one apart from the many smaller ruins called zimbabwes, houses of stone.

What did the city live on? A significant part of its wealth came from controlling the trade routes from the goldfields of the Zimbabwean plateau to the Swahili coast. Archaeologists have excavated Chinese pottery shards, coins from Arabia and glass beads there. Cattle mattered too: a large herd that supplied the city moved seasonally and was managed by the court.

The most treasured finds are eight soapstone birds, thought to represent the bateleur eagle, a messenger of god in Shona culture. A modern nation took its name from the site in 1980 and put the bird on its flag. Why the city was abandoned is unknown; Shona oral tradition blames a salt shortage.