Imagine the folks who built the Roman Colisuem, and all those beautiful medieval cathedrals. How did they get all that stone way up on the upper floors? For the larger stones, it would have taken a whole team of men to carry each one to those heights. But that wasn't necessary, because they had machines. Guédelon Castle is being built using 13th-century technology to build it. That includes a treadwheel crane, also called a treadmill crane. Using a large wheel with a person walking inside, they transfer the distant walked into lifting power through pulleys. Tom Scott demonstrates the treadmill crane at the Guédelon Castle construction site.