Scientiststo reveal secrets of ancient Aztec city
Archaeologists are to open a long-sealed cave under a Mexican pyramid in the hope that it will unlock the mystery of one of ancient civilisation's greatest cities.
With its soaring stone pyramids and geometric temples, Teotihuacan was once the biggest city in the Americas, and possibly the world.
However, experts have never been able to say with certainty who built it, or why it was suddenly abandoned.
An international team of experts believes the answer may lie under the Pyramid of the Sun, the centre point of the vast ruined city, 25 miles outside Mexico City.
At the end of this month, they are to investigate a man-made tunnel and cave system beneath the pyramid, the third largest in the world, to test theories that it was used for rituals including human sacrifice.
"We think it had a ritual purpose. Offerings were placed at the very end of the tunnel as part of the pyramid's construction process," said Alejandro Sarabia, Teotihuacan's director of archaeology.
"We want to find out why the Teotihuacan people sealed it and when," Mr Sarabia said. "Excavating the cave could give us some clues about what happened at Teotihuacan, about the fate of the city."
At its zenith between 150AD and 450AD, Teotihuacan was home to up to 200,000 people of various ethnic origins and is thought to have been larger than any European city at the time, including Rome.
But sometime in the 7th or 8th century, it was set ablaze -- possibly as the result of an insurrection -- and abandoned.
The Aztecs believed the city was divine and identified it with the place where the sun was created. They also gave it its name, which roughly translates to: "The place where men became gods".
The tunnel entrance was discovered in 1971 by workmen installing a sound and light show for the pyramid. After initial tests, it was dismissed as a natural cave and sealed two years later. Much of the information about it was lost.
Mr Sarabia said the cave was abandoned and covered over, but experts do not know why.
"We have found some small stone artefacts from the Teotihuacan period but also some indications of Aztec presence," he said. "If we can find out what happened, when, and perhaps how, it will give us a better idea about the history" of the pyramid and of the city in general.'' (© Daily Telegraph, London)