At its peak, in the late 12th Century, Angkor was a bustling metropolis covering 1,000 sq km. (It would be another 700 years before London reached a similar size.)

Alan B wrote:Got it set to series link: BBC 2 Thursday 25th at 20:00.

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.

Sendraks wrote:That is pretty darn amazing. A pretty staggering insight into exactly how well developed earlier civilisations were and how much we've fallen back as a species. Imagine what the world would be lack if the Khmer had been left to continue to develop their civilisation.

Spearthrower wrote:Earlier

2014 > 1200 - I have a feeling the math works out!