From Wikipedia

Great Zimbabwe

 Great Zimbabwe is a ruined city that was once the capital of the Kingdom of Zimbabwe, which existed from 1100 to 1450 AD during the country’s Late Iron Age. The monument, which first began to be constructed in the 11th century and which continued to be built until the 14th century, spanned an area of 722 hectares (1,784 acres) and at its peak could have housed up to 18,000 people. Great Zimbabwe acted as a royal palace for the Zimbabwean monarch and would have been used as the seat of their political power. One of its most prominent features were its walls, some of which were over five metres high and which were constructed without mortar.

 Eventually, the city was largely abandoned, and fell into ruin, first being encountered by Europeans in the early 16th century. Investigation of the site first began in the 19th century, when the monument caused great controversy amongst the archaeological world, with political pressure being placed upon archaeologists by the-then white supremacist government of Rhodesia to deny that it could have ever been produced by native Zimbabweans. Great Zimbabwe has since been adopted as a national monument by the Zimbabwean government, with the modern state being named after it. The word "Great" distinguishes the site from the many hundreds of small ruins, known as Zimbabwes, spread across the Zimbabwe highveld. There are 200 such sites in southern Africa, such as Bumbusi in Zimbabwe and Manekweni in Mozambique, with monumental, mortarless walls and Great Zimbabwe is the largest.