Deep beneath a pyramid in central Mexico lies a glittering, hidden landscape. Instead of water, ancient architects used pools of liquid mercury to build its silver rivers.
In 2015, a team led by archaeologist Sergio Gómez reached the end of a sealed, 340-foot-long tunnel beneath the Temple of the Feathered Serpent in the ancient city of Teotihuacan. Inside the subterranean chambers, they found large quantities of liquid mercury alongside jade statues, large shells, and rubber spheres.
The mercury was not used for any practical or industrial purpose. In the ancient world, extracting it was an arduous process that required continuously heating crushed cinnabar ore until the mercury vaporized and condensed. Because of the sheer effort required to produce it, and its mesmerizing, unearthly appearance, the metal was highly prized and considered deeply sacred.
Archaeologists believe the people of Teotihuacan used it to build a miniature cosmos. To them, these reflective, metallic pools represented the subterranean lakes and waterways of the underworld. The entire tunnel system was designed to mimic the realm of the dead; its walls were impregnated with powdered pyrite (fool's gold) so that they would glitter like the night sky when illuminated by torches. The liquid mercury formed the watery boundary of the afterlife, placed directly beneath the city's ceremonial center.
While Teotihuacan is the only excavated pyramid with this feature, it is not the only ancient monument tied to mercury. Ancient Chinese historians wrote that the First Emperor, Qin Shi Huang, had the rivers and oceans of his empire recreated with flowing mercury inside his massive, unexcavated tomb mound. Modern soil tests above the emperor's burial site have consistently revealed abnormally high levels of mercury, showing that rulers on opposite sides of the ancient world independently used the rare metal to build eternal, silver rivers in the dark.