We have now done two trips to South Dakota and seen a lot of the national parks and monuments in the area. The most well known of course iS Mount Rushmore which is definitely worth a visit if you are in the area, but there is a lot of other stuff to see also. There are two large caves including Jewel Cave National Monument and Wind Cave. Their is the BlacK Hills National forest and Custer State Park. My favorite is probably Badlands National Park as it is so different from everywhere else.