Have you been to the House on the Rock?
It's a tourist attraction in Wisconsin.
Decades ago, a man decided to build a house on that rock and he turned it into spectacle. It opened in 1959, and is now a full fledged resort with gigantic rooms filled with oddities of yesteryear. I went there some twenty years ago, and it took about 5-6 hours to get through. I don't remember a lot of it because there was just so much stuff. Sensory overload.
If you've never been there, don't expect some sort of educational odyssey, just expect to look at a lot of strange things. Don't think of it as a museum trip, think of it as going to a Barnum and Bailey show.
Still, I can help but think there's material here to inspire a RPG scenario. You have an enigmatic figure who built a house on top of a rock, filled with galleries of treasures. Rumor has it that most of the treasure is false, but what is real and what isn't? What is the fabled Infinity Room? Is it true that the Organ Room was inspired by Dante's Inferno?
No really, I'm serious, take a look at some of these pictures from the House on the Rock's website:
The World's Largest Indoor Carousel.
Now imagine that's some sort of evil contraption the adventurers must destroy but there's those winged demons trying to stop them.
Here's a closer look of the carosel--with an evil looking doll on it! It she the leader of all the evil dolls in the place--a carrionette straight out of the Ravenloft adventure The Created?
A strange fire place and nearby shelf full of ancient tomes and grimoires--but are they real... or fake? Just ignore the "Tour Continues" sign.
The Infinity Room--where does it go?
If you deep enough, you're discover whole other town--a merrier version of the Vault of the Drow?
The medievalist in me cringes.
You can find more at The House on the Rock website.
Here's more about the House's history on Wikipedia.