The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Site of the 1879 Cheyenne Outbreak and the site where famed Sioux chief Crazy Horse met his fate.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A trading post in the North Pole where children send letters.

The king of U.S. high points towers over every other peak on the continent.

The eccentric mansion of one the most popular horror authors of modern times.

This large cemetery is known as the museum of granite sculptures.

This unusual building straddles two countries.

The sweetest graveyard in the world is filled with headstones for dearly de-pinted ice cream flavors.

Elvis's own personal tropical hideaway.

The world's longest known cave system.

"The Most Boring Road in the State."

As its grandiose name implies, this wooden dome is unsurpassed in size.

This lighthouse and shipwreck museum keep a torch burning for the memory of the SS Edmund Fitzgerald.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.

This lovely public park has an intriguing past and unique wooden bridges made of concrete.

This national park on the shore of Lake Michigan features remarkable dunes that lie at the heart of a Chippewa legend.

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

Hell on Earth is actually a small town in Michigan where anyone can be mayor for a day.

A rim-made reptile in North Dakota.