With new technology, Allan Maca explores a lost ancient megacity that 4,000 years ago was one of the biggest on the planet. But why did it disappear?

Many believed the lost city of Xanadu was a myth, but with cutting-edge technology, Dr. Allan Maca brings Kublai Khan's legendary city back to life.

The Great Wall of China is an icon of the ancient world. But only now, thanks to cutting-edge technology, are its secrets finally being revealed.