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

Deep scars on the earth left by the Ice Age.

A monument to one of the few Olympic flames ever to be lit outside of the host city.

Thirteen pastel palaces in downtown Charleston add a gorgeous splash of color to the city.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

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

An architect's childhood fantasy treehouse made real.

A beautiful geyser under environmental threat.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.

This rustic old building is said to be the most photographed barn in America.

This legendary urban waterfall creates a dazzling display of rainbows.

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

This World War II-era bunker is now packed with posters and props from movies and TV shows filmed nearby.

A glass display case holds the document that ended the Second World War—which one person signed on the wrong line.

A one-stop shop for all things snowmobile, started by a snowmobile-obsessed group of friends in Wisconsin.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

Inside houses a vast collection of military aircraft and missiles spanning the ages.

A real flying saucer, contracted by the U.S. Air Force.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

Rare recess caves fill this unbelievably beautiful Ohio park.

An office built to look like a giant basket.

A unique collection of military history dating back to the American Revolution.