Not your traditional NP, but quaint and beautiful. Relax, take in the view from atop mountain tower, and tour Fordyce.
The $7 is well worth the stunning views! Be sure to see both the open air top level & the enclosed 2nd floor. Lots of great information and displays about the history of Hot Springs is provided there.
If you're looking to try the bath houses cheap go to Quapaw. They offer just a soak for around $15. Make sure you bring water shoes or sandals.
