Inca fortress of Sacsayhuamán near Cusco, Peru

A piece of Inca history

It's the 1530s, Spanish conquistadors cemented their hold over the lands of the Incan Empire, including the massive 12th-century stone fortress in today's image: Sacsayhuamán, in the old Inca capital of Cusco. Here, the Spanish held prisoner a man named Manco Inca, the puppet leader they'd installed over the Incans. But one day in the spring of 1536, he escaped.

Today is the anniversary of the day he returned, accompanied by legions of Inca warriors. The Incas retook much of Cusco, including Sacsayhuamán, which they made their main base, forcing the Spanish to take refuge in buildings near the main plaza. In the end, the Incan effort failed: after a few months, the Spanish won back Sacsayhuamán and then cut off the Incans' supplies, forcing their surrender and finalizing Spain's control over Peru.

Sacsayhuamán was eventually dismantled and its pieces of it were used to build colonial Cusco. But even today, the outer walls of impossibly large interlocking stones still overlook the modern-day city, a symbol of the mysterious empire that once ruled here.