Tunnel at ancient Mexican site may hold tombs

A long-sealed tunnel has been found under the ruins of Teotihuacan and chambers that seem to branch off it may hold the tombs of some of the ancient city's early rulers, archaeologists said.

Experts say such a discovery would be significant because the social structure of Teotihuacan remains a mystery after nearly 100 years of exploration at the site, best known for the pyramids of the Moon and the Sun. No depiction of a ruler, or tomb of a monarch, has ever been found, setting the metropolis apart from other pre-Hispanic cultures.

Archaeologists suspected the hidden tunnel was there after a rainstorm in 2003 caused the ground to sink in the central ceremonial area of the ruins, just north of Mexico City. After eight months of excavation, they reached the roof of the tunnel last month. They lowered a small camera into the 12ft-wide corridor, and got the first glimpse of the space that they say was intentionally closed off between AD200 and 250.