MEXICO CITY, MEXICO—Archaeologists from the National Anthropology and History Institute plan to use a robot to investigate the far reaches of a tunnel found beneath the Temple of the Plumed Serpent at Teotihuacan. The chamber is estimated to be 2,000 years old, and may have been used as a place for royal ceremonies or burials. The three-foot-long robot is equipped with arms to deal with any obstacles it may encounter on the journey.