A natural gas leak provides a flickering flame beneath a waterfall.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

Niagara Falls holds a special place in Nikola Tesla's history, so they put a statue on it.

This functioning mill was built in the 1970s using parts from several other West Virginia mills.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

A bizarre roadside attraction and the first instance of miniature golf in the world.

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

Once decrepit and slated for demolition, now one of the longest pedestrian bridges in the world.

Hidden behind Lincoln's head is a chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

The largest cemetery in Louisville is the final resting place of Col. Sanders and Muhammad Ali.

The grave of America's 11th president is not in some grand monument but instead it's hidden away on the grounds of the Tennessee Capital.

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

Home of an evil witch famous within southern folklore.

The only arched bridge made of stone on the entire Mississippi River.

Downtown Minneapolis mixed art and function by turning some of their sewer covers into works of art.

One of the world's premier laboratories for hydraulic engineering research takes full advantage of the water's power.

When flour explodes, it's not a pretty sight.

Vice President Humphrey's final resting place is tucked away in this cemetery along with a few other notable figures.

This small, but beautiful waterfall has attracted visits from artists, composers, and two United States presidents.

More than 7,000 gallons of water pour over these cascading red quartzite waterfalls every second.

The only brothel on the National Register of Historic Places.

The last location where Buddy Holly, Ritchie Valens, and J. P. "The Big Bopper" Richardson played before their tragic deaths.