Griff Rhys Jones did a series of the world's greatest cities, and when he covered Paris he met with the group of restorers and followed them through a massive n

Griff Rhys Jones did a series of the world's greatest cities, and when he covered Paris he met with the group of restorers and followed them through a massive network of underground tunnels, wherein they could access almost any building in Paris, they claimed to have keys to many of them. It was a terrific documentary. It's available here: https://www.youtube.com/watch?v=5OiL8oVj0sA https://www.youtube.com/watch?v=5OiL8oVj0sA (~45 minutes)