In 1860, missionaries came across ruins in the Cambodian jungle and discovered a lost city twice as large as Manhattan.
Why did the Maya abandon their magnificent city of Chichen Itza?
Scientists decode the life-giving riddle of Bolivia's great Akapana pyramid.
High in the Andes, an ancient Inca city flourished and was subsequently abandoned, lost to the outside world for centuries. Why was it built and deserted?