In France, on the coast of Normandy, in a vast bay swept by the most powerful tide in Europe, stands the Mont-Saint-Michel. Both a masterful abbey and an impregnable fortress, this silhouette is known around the world and attracts nearly 3 million visitors each year. Yet the Mont Saint-Michel is far from having revealed all its secrets. Today, with the help of the latest technology, experts now have the means to scrutinize this site on all scales and try to fill in the gaps of its fascinating history. By viewing this monument from different points of view, using satellite images and microscopic details, archaeologists, scientists and historians are making groundbreaking discoveries about the history of this amazing structure. It was already built in the Middle Ages, but there are still many questions around.