Remains of ancient ‘pyramid city’ as densely built up as Manhattan have been discovered in the heart of Mexico, thanks to pioneering imaging techniques.

Experts used lasers to send beams of light from an aircraft to the ground below, measuring the reflected pulses to build up a map of the region.

They discovered a lost pyramid city known as Angamuco built by the Purépecha, rivals to the Aztecs, around 1,000 years ago.

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The discovery was made by a team of researchers, including Colorado State University (CSU), about a half an hour’s drive from Morelia, in the central Mexican state of Michoacán.

‘To think that this massive city existed in the heartland of Mexico for all this time and nobody knew it was there is kind of amazing,’ said Chris Fisher, professor of anthropology at CSU who made the admission of missing the finding on foot.

Traditional methods of on-the-ground archaeological surveys would take 20 years to assemble as much data as two days using the laser-based technique, known as Lidar ranging, according to experts.

A particular benefit of the technology is its ability to penetrate through vegetation, which is dense in many of the forest areas being surveyed.

Seeing the results, one of the team realised he had walked within 30 feet (10 m) of one of the largest pyramids on the Angamuco site without realising it, due to the thick undergrowth.

‘If you do the maths, all of a sudden you are talking about 40,000 building foundations up there, which is [about] the same number of building foundations that are on the island of Manhattan.’

Using Lidar, researchers found that the recently-discovered city was more than double the size of Tzintzuntzan, the culture’s capital, at 10 square miles (26 sq km).

However the city, built over an ancient lava flow, was probably not as densely populated, with around 100,000 people thought to have called it home at its height, between 1000 and 1350AD.

Imaging also revealed that Angamuco was laid out in an unusual configuration, with monuments like pyramids and plazas dotted around eight zones on the edges of the city rather than concentrated as a focal point in the centre.

The findings, which were announced during the 2018 AAAS Annual Meeting in Austin, Texas, have implications for understanding the region’s history of migration, land use and conservation and even early climate changes, participants said.

Using airborne mapping, researchers are discovering new archaeological sites that show pre-Columbian Mesoamerica was ‘significantly more densely populated at the time of European contact’ than previously thought.

Professor Fisher pointed to a previous city he has studied in the Mosquitia Rainforest of Honduras.

Thousands of Mayan people lived in complex cities with central plazas, pyramids, reservoirs, canals and terraced farmlands in this area 1,000 to 2,000 years ago…..more here