Originally a 10-story 600,000 square foot shoe factory, it was bought by artist/sculptor Robert Cassilly (who clearly was nuts) as a place to display his art.
What is really is, is a playground on steroids meant for as many ADHD kids as possible to enjoy at the same time. The noise level is deafening. Tip - go when school is out and not every kid in St Louis is there on a class trip.
Here is a question for you to ask:
Q - How did I get so many photos without hordes of kids in them?
A - It wasn't easy