South Dakota sight seeing all fun stuff

NEVER EVER BEEN to this State going to famous Sturgis too bad not during all the VROOM VROOM FUN what it is known for LOL and going to see Mount Rushmore then driving ALLLLLL the way to Iowa and Nebraska.
Any other sites I should see?
SOmeone told me of a huge indian carving?

Made it to Sioux Falls was surprised it is on the same time Zone as Texas.
And still Casinos every where woop woop yay me