Researchers open secret cave under Mexican pyramid | Science | Reuters

Researchers open secret cave under Mexican pyramid | Science | Reuters:

"MEXICO CITY (Reuters) - Archeologists are opening a cave sealed for more than 30 years deep beneath a Mexican pyramid to look for clues about the mysterious collapse of one of ancient civilization's largest cities.

The soaring Teotihuacan stone pyramids, now a major tourist site about an hour outside Mexico City, were discovered by the ancient Aztecs around 1500 AD, not long before the arrival of Spanish explorers to Mexico.

But little is known about the civilization that built the immense city, with its ceremonial architecture and geometric temples, and then torched and abandoned it around 700 AD."

I was able to visit this site in 2002 during a two week stay at CIMMYT, near Texcoco (a little east of Mexico City). The Teotihuacan pyramids are a truly awesome site, and climbing the steep steps of the Pyramid of the Moon was an aerobic exercise made more difficult by an elevation exceeding 7400 feet. I did get several nice images:

Here is the Pyramid of the Moon, which in 2002 only allowed access
to the second landing due to ongoing archaeological research.

These steps are roughly knee-high and for someone who already
had knee issues, that rail was quite necessary.

The Pyramid of the Sun seen from the Pyramid of the Moon.

Looking to the side of the Pyramid of the Moon revealed these unexcavated
structures, including what seems to be a smaller pyramid on the left.

A lot of nice stonework can be seen all over the Teotihuacan site, replicas of which
can be seen in the Museo Nacional de Antropología.