The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

The world's longest known cave system.

A ceramic-tiled room at the Seelbach Hotel said to have secret tunnels used by Al Capone and a crowd that helped inspire F. Scott Fitzgerald's 'The Great Gatsby.'

The longest navigable underground river in the United States is home to countless blind and albino animals.

Tucked away in the forests of Indiana resides an abandoned waterslide that is now a popular graffiti haunt.

A collection of sculptures and trails that appear to change with the seasons.

Eight rare Corvettes are swallowed up by a sinkhole in Kentucky's National Corvette Museum.

A local scoured more than 1,000 acres for stone to create his masterpiece.

Visitors to this arboretum are greeted by three smiling giants crafted from sustainable materials.

This whimsical park encourages its visitors and wildlife to roam on and around the various works of art.

One of Chicago's last seafood smokehouses perfects a dying breed of fishcraft.

This historic-shipwreck-cum-diving-spot can still be seen poking its boiler out of the Lake Michigan waters that claimed it.

Wisconsin's most celebrated export gets the royal treatment on I-94.

A unique botanical garden housed in three giant geodesic domes.

This striking art museum holds an amazing series of curiosity cabinets.

A trailblazing sovereign nation tucked in the American state of Wisconsin.

A group of artists transformed this desolate city alleyway into an outdoor gallery of street art.

Watch the ships come in on Michigan's 210 ft. high observation deck in Sault Ste. Marie.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The world's only bushplane museum captures the spirit of the early planes and pilots and their contributions to northern life in Canada.

Two dozen rescued bears roam (mostly) free at the largest bear ranch in the U.S.

This freshwater spring fills with 10,000 gallons of water per minute.