Robot used in archaeological site

A robot has discovered three ancient chambers at the last stretch of unexplored tunnel at Mexico's famed Teotihuacan archaeological site on Monday (April 22), the first robotic discovery of its kind in the Latin American country.

Named Tlaloc II after the Aztec god of rain, the robot was first lowered into the depths of the 2,000-year-old tunnel under the Quetzalcoatl Temple to check if it was safe for human entry.

After months of exploration, the remote-controlled vehicle has relayed back video images to researchers of what appears to be three ancient chambers located under the Mesoamerican city's pyramid.

The investigation's immediate goal is to find a tomb where the city's former rulers are thought to be buried.

Declared a UN World Heritage site, Teotihuacan reached its peak between 250 and 500 AC when it had a population close to 150,000 residents to become the sixth largest city in the world after Constantinople and Alexandria.

The city has an area of