In France, a man walks on what can only be described as a human-sized hamster wheel. The wheel moves around and around, as the man keeps walking. What is he doing? He is lifting a heavy object to the top of a tower the same way workers moved such objects 800 years ago. In the 13th century, workers did not have the 100-meter tall cranes they now use to build tall buildings. So they had to be creative and come up with simple machines to get their work done. The man on the large wheel is walking at a reasonable speed. The wheel turns and pulls a rope connected to a pulley at the top of the tower. Another rope tied to the pulley lifts supplies from the ground. This is just one way skilled craftsmen are building a 13th-century castle without using modern tools. Crews have been working on the castle since 1997.