Upside-Down White House [Wisconsin Dells, WI, USA]
There are several upside-down White Houses in the U.S. The one located in Wisconsin Dells, a city in south-central WI, is the largest of them, and also the only one with its insides being upside-down as well.
So if you're ever in Wisconsin Dells, I'd recommend that you take the time to tour the upside-down White House or at least stop by and take a quick picture! :)
I am not sure if much has changed since summer 2013, but back then for only $5 per person you could get inside the building and enjoy a tour. It was definitely worth it! Our tour guide was such a great actress; she managed to scare me a few times during those 15 or so minutes (even though that's not too hard to do :D).