Parque Nacional Bosque de Tlalpan

This guide to Parque Nacional Bosque de Tlalpan in Mexico City follows the lava field left by the volcano Xitle over two thousand years ago, and the settlement of Cuicuilco buried beneath it. You'll hear from Cesar Sanchez, who oversees the city's protected natural areas, about how the porous black rock quietly recharges the aquifer millions of people still drink from, and why that same broken stone turns treacherous each dry season. It closes with the forest's stranger residents, including a tarantula found nowhere else on Earth.