Hidden Treasure just outside Madison

I've been living in Madison for the past 5- 6 years. But I always go to further places to find something 'cooler' because I thought there's nothing to see in Madison. Then my parents came to visit. I tried to find something that both my mom and dad will like. And close! They hate stucked in the car for more than 3 hours. They already having trouble stay in the car on the the way to Chicago.
Anyway, my roomate suggested Cave of the Mound. I thought... it will be such a tiny little cave that not even worth my money. So, since it's closer and cheaper than House on the Rock, we decided to check that place out.
To my surprise, the Cave of the Mound was impressive. I couldn't believe such beautiful cave even exist only half hour from Madison. My dad was impressed. My mom love the beautiful rocks and minerals. In short everybody, even my two roomates and myself enjoyed the trip.
So, like the old indonesian saying: Gajah di depan mata tak terlihat, semut di sebrang lautan tampak jelas... (You cannot see the elephant right in front of you, but you are sure about the ants across the sea..... or something like that).