How lasers revealed a lost city

Deep in the Cambodian jungle lie the remains of a vast medieval city, which was hidden for centuries. New archaeological techniques are now revealing its secrets – including an elaborate network of temples and boulevards, and sophisticated engineering.

In April 1858 a young French explorer, Henri Mouhot, sailed from London to south-east Asia. For the next three years he travelled widely, discovering exotic jungle insects that still bear his name.

Today he would be all but forgotten were it not for his journal, published in 1863, two years after he died of fever in Laos, aged just 35.

Mouhot’s account captured the public imagination, but not because of the beetles and spiders he found.

Readers were gripped by his vivid descriptions of vast temples consumed by the jungle: Mouhot introduced the world to the lost medieval city of Angkor in Cambodia and its romantic, awe-inspiring splendour.

“One of these temples, a rival to that of Solomon, and erected by some ancient Michelangelo, might take an honourable place beside our most beautiful buildings. It is grander than anything left to us by Greece or Rome,” he wrote.

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His descriptions firmly established in popular culture the beguiling fantasy of swashbuckling explorers finding forgotten temples.

Today Cambodia is famous for these buildings. The largest, Angkor Wat, constructed around 1150, remains the biggest religious complex on Earth, covering an area four times larger than Vatican City.

It attracts two million tourists a year and takes pride of place on Cambodia’s flag.

But back in the 1860s Angkor Wat was virtually unheard of beyond local monks and villagers. The notion that this great temple was once surrounded by a city of nearly a million people was entirely unknown.

It took over a century of gruelling archaeological fieldwork to fill in the map. The lost city of Angkor slowly began to reappear, street by street. But even then significant blanks remained.

Then, last year, archaeologists announced a series of new discoveries – about Angkor, and an even older city hidden deep in the jungle beyond.

An international team, led by the University of Sydney’s Dr Damian Evans, had mapped 370 sq km around Angkor in unprecedented detail – no mean feat given the density of the jungle and the prevalence of landmines from Cambodia’s civil war. Yet the entire survey took less than two weeks.

Their secret?

Lidar – a sophisticated remote sensing technology that is revolutionising archaeology, especially in the tropics.

Mounted on a helicopter criss-crossing the countryside, the team’s lidar device fired a million laser beams every four seconds through the jungle canopy, recording minute variations in ground surface topography.

The findings were staggering.

Lidar technology has revealed the original city of Angkor – red lines indicate modern features including roads and canals

The archaeologists found undocumented cityscapes etched on to the forest floor, with temples, highways and elaborate waterways spreading across the landscape.

“You have this kind of sudden eureka moment where you bring the data up on screen the first time and there it is – this ancient city very clearly in front of you,” says Dr Evans.

These new discoveries have profoundly transformed our understanding of Angkor, the greatest medieval city on Earth.

Source: BBCNews Read and see more

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