Cleveland's giant "free" stamp is a nod to the Civil War, but was misinterpreted for years.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

Yo, Adrian!

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.

The unbelievably opulent home built for an infamous newspaperman.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.

Quite simply the largest tree in the world (by volume).

A hotel and restaurant serving as the mecca of kitsch.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

The world's longest known cave system.

Home to items never before seen by the public.

The first declared National Monument in the United States.

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

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

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

These pretty kitties killed and ate as many as 135 railway workers.

Patrick Dougherty's fantastic living tree sculptures, mind-blowing but temporary.

Symbolic attempt to overcome the issues of life.