Archaeologists have discovered a secret passageway under Teotihuacan’s Pyramid of the Moon that may have been used to emulate the underworld. It’s located about 30 feet underground and spans from the pre-Aztec pyramid to the middle of its outer central square. “The function of the tunnel may have been to reproduce the underworld, a world where life, animals, and plants originated,” said archaeologist Veronica Ortega. Construction first began on the Pyramid of the Moon in 100 BC, which began as a small platform that grew in stages over roughly 500 years to a height of 150 feet. Click here to view the first image in today’s viral picture gallery. Continue reading for a viral video of someone exploring an abandoned fortress.