St. Louis Science Center, and went multiple times each year. I haven't been been there in a long time; when Tony suggested we go today it sounded good to me.
They've done some remodeling since my last visit. In the lobby, there was a fascinating display. The Energizer Ball Machine is a huge kinetic sculpture that's three stories tall and almost as wide as the lobby. It has balls that move up and down through spirals, funnels, loops, and slides. The machine is powered by kinetic energy that's supplied by a treadmill that resembles a giant hamster wheel. It looked like anyone could take a turn walking on the wheel, so I got in line to operate the Energizer Ball Machine at the Science Center.
Tony decided not to join me in my adventure, so I felt a little strange. I was the only adult in the line; everyone else was under 10 years old. When it was my turn I joked with the attendant how I was decades older than anyone else. I felt better when he indicated that there was no age limit to participate.
Operating the machine was harder than I thought it was going to be. The "wheel" was about six feet in diameter, and had a bar to hold on to as you ran. I easily started the wheel spinning, but after about 30 seconds I was winded and ready to stop. I was happy to step off and give my place to the next person in line.