A thousand years ago the Khmer people of Cambodia built an empire that stretched a million square kilometers. It became the largest superpower the region has ever seen. Their capital was the great city of Angkor, once the largest city on Earth. Its centerpiece was Angkor Wat - a vast temple complex covering an area more than four times the size of Vatican City. But 600 years ago the Khmer kings abandoned their capital and many of the huge structures they built were devoured by the jungle. Ever since, the people who once lived around the temples have remained an enigma. Little is known about the kings who secured their vast empire or how they constructed the wonders of Angkor Wat. In the first of this two-part series, an international team of archaeologists and scientists use revolutionary technology to reveal the true scale and extent of the lost city of Angkor and to find out how its people lived and died. Using a new laser scanning technology called LiDAR, they discover the secrets ...