The St. Louis Gateway Arch, which is the nation's tallest monument at 630 feet.
It was completed in 1965, with nine hundred tons of stainless steel, at a total cost of $13 million. We watched the movie about the construction and none of the workers wore safey harness equipment. The margin for error in assembly was 1/64". Whew!
The Museum has many of the talking figures to tell the story of St. Louis but one of them is unclothed so the innards can be seen. Fascinating but a little kinky.