The shaman, who had introduced himself simply as Águila—Eagle—led us inside the building. The interior consisted of a number of long, narrow rooms, all empty and with floors covered with wind-blown dust and bits of broken stone. At first I wondered why we had come here, but then Águila pulled a magkey out of his pocket and slotted it into what looked like an ordinary crack in the stonework. I heard the hum of an electric motor and stepped back warily as a portion of the floor slid open, revealing a flight of stone steps. Dust trickled into the opening.