Badger State Trail Tunnel
Wisconsin is one of the top five coldest U.S. states in winter but that is also the best season to see the Stewart Tunnel. This old railroad tunnel is in the optimal place for natural ice sculptures to form. Rock-solid stalagmites are created when high-speed winter winds race through the tunnel carving wondrous shapes out of the blocks of ice. If you can't make the trip in the winter, the tunnel with its pretty stone structure is still worth visiting in the warmer months when it is surrounded by the green foliage of the surrounding forest.