Yet there are still portions of Teotihuacan that remain untouched by today's explorers, including a subterranean burial site that scientists estimate has spent the last 1900 years unseen by human eyes. Until now.
In 2003, scientists discovered a tunnel beneath Teotihuacan's Temple of the Plumed Serpent. They speculated that the tunnel was a processional walkway leading to a warren of royal burial chambers, but couldn't say for sure, since the opening to the tunnel was intentionally buried by the city's last inhabitants. According to BLDGBLOG, archaeologists at Mexico's National Anthropology and History Institute are now uncovering the mystery of the buried chambers without disturbing them - thanks to a diminutive robotic system designed to go where shimmying archaeologists cannot:
... A little wireless robot called Tlaloc II-TC will soon "investigate the far reaches of a tunnel found beneath the Temple of the Plumed Serpent at Teotihuacan," entering a chamber "estimated to be 2,000 years old, and [that] may have been used as a place for royal ceremonies or burials."