Erected at 2430 meters high on a rocky crest in the heart of the Peruvian Andes, the city of Machu Picchu remains in the eyes of many this civilization's most breathtaking and enigmatic urban creation. This extraordinary sanctuary, a UNESCO World Heritage Site, still holds many mysteries. But today, using state-of-the-art technology, experts now have the means to go back in time to probe the invisible, to explore what lies beneath and around this ancient city, and reveal its secrets.

On the planet's largest continent, in Asia, the Great Wall of China spans the country from East to West: but this enigmatic monument is still shrouded in mystery. Thanks to the latest digital technology, today's experts now have the means to scrutinize this UNESCO World Heritage site from all perspectives and scales, from the infinitely far to the infinitely close. History, science, construction… they dissect the work of ancient builders to try to reveal secrets kept for millennia.