One of the most interesting and controversial curiosities in Minnesota’s history was found on a farm outside of Kensington, MN in 1898. Allegedly a farmer unearthed a rock slab that was tangled in some tree roots and after cleaning it off, discovered ancient runic carvings. The writing, Scandinavian in nature, revealed that explorers had been over here long before Columbus, and had gotten as far as Minnesota.
Unfortunately, there is a sharp divide as to who considers it authentic vs. a hoax. It seems no notable scholars truly agree that it is real, and most Minnesotans are too stubborn to accept that answer. So, the jury is still out. The real Runestone is somewhere being studied in Washington currently, but there is a replica at the Minnesota History Museum in St Paul, MN (pictured below).
The Runestone Museum is in Alexandria, MN where you can learn all about the detailed history of this artifact, as well as buy all sorts of trinkets relating to the Viking lore. It sits right next to Big Ole and the Minnesota Lakes Maritime Museum as well.
While in the area: Downtown Alexandria has a lot of antique and other cool shops, and there are walking paths around the lakes right in town.