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

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

The first declared National Monument in the United States.

It was once the base for a series of domestic terror attacks.

These unusual rooms on wheels are holdovers from the 1960s.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

At 207 feet, one of the world's longest continuous escalators.

Stand at the center of this lakefront sundial, and you'll become part of the timepiece.

This 38-drawer structure claims the superlative title, but it isn't the world's only giant filing cabinet.

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

A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

Come for the speed, leave in love with the desert.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

Locals dubbed it the "Owl Building" because of its bird-like appearance.

This downtown Dallas art installation is always on the lookout.

An emerald-green grotto just a short trip from Austin.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

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

Rhode Island's tallest building bears a resemblance to the "Daily Planet" building and has been empty for more than five years.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

This tiny little island has, as the name says, just enough room for its single house.

Surprisingly aquamarine waters fill deep lakes formed at the end of the last ice age.