One in the Wisconsin Dells too, but I can’t remember the name of it. Now I’ll have to go and look it up to see if it’s still there (last time I in the Dells was a good 20 years ago).
http://www.roadsideamerica.com/news/14477
Mystery Spot Vanishes, A Mystery Road Is Born?
Since 1952, the southern approach to the Wisconsin Dells/Lake Delton, Wisconsin, tourist mecca has been guarded by The Wonder Spot, one of many mystery spots scattered across America. Discovered in 1948, The Spot is nestled in the woods south of the lake, conveniently only about a half-block off of Hwy 12. Its powers were strongest in The Wonder House, a clapboard shack “where the laws of natural gravity seem to be repealed,” according to The Wonder Spot's brochure.
NOTE: There is a live link there for other locations of "Mystery Spots" around the country...