In 1871, Karl Mauch, a German geologist, arrived at the ruins of Great Zimbabwe in what is now southern Zimbabwe in sub-Saharan Africa. Local Karanga tribesmen led Mauch to the wooded savanna location where he viewed 100 acres of granite enclosures. The sinuous coursed granite walls were built without mortar and stood up to 32 feet high. Maunch was the first European to investigate the ruins, but centuries earlier João de Barros had written what he had heard about them (but not himself seen) in his Da Asia (1552) record of Portuguese conquests. Subsequent investigators were inept, racist and attributed the construction to whites, until David Randall-MacIver wrote his account in 1906 of their true native African origin.«[Image: aerial view of the Great Zimbabwe ruins.]