When you imagine the word "unique", it's hard to come up with a better definition of that than a 55 million square foot man-made cave. That is exactly what has just been declared the most unique place in Missouri.
If you're interested in preparing for a worst-case scenario in the world, you might want to consider a mammoth limestone cave that is hidden from society that lies underground right across the Missouri border and it's available - for a price.
I will confess that I only think about sinkholes when I see one appear and that's not frequently. There have been some that have been spotted in Missouri recently which led me on an investigation where I learned that the state is a dangerous sinkhole hotspot.
I don't get the chance to adventure as much as I used to. Fortunately, I can vicariously live through the journeys of others including two adventurers who recently shared what it's like inside the caverns of Cave-In-Rock State Park in southern Illinois.
If you found a mysterious hole in the ground, would you grab some rope and descent down into it? A group of explorers did and learned the unknown hole they found went down over 200 feet into the Earth.