Imagine walking through the hills of southern Africa and stumbling upon a 1,700-acre stone metropolis built entirely without mortar, its granite walls towering 36 feet high. When European colonizers found it, they refused to believe Africans could have built it, and the lie that followed became a state-sponsored war on the truth.

This episode traces the rise and fall of Great Zimbabwe, the largest pre-colonial stone structure in southern Africa. We explore the ingenious engineering behind its mortarless walls, the cattle-and-gold economy that funded a medieval empire, the global trade that brought Chinese porcelain to an African king's table, and the century-long battle over who has the right to control its history.

• How builders used fire and cold water to crack granite into ready-made bricks, then locked walls together with a ba ...