This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

The highest point in Montana is as rugged and singular as the state itself.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

A hollow cement depiction of time's inexorable effect on the human body.

These mansions date back to Chicago's days as a brewer's paradise.

See massive fossils that are over 200 million years old in northeastern Arizona.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Plot your trip through the city on the sidewalk.

The 28-foot granite map plots the locations of 40 theaters in New York City.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

More gold than anywhere else, ever.

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

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

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

A hidden garden of stones engraved with scriptures, a Joseph Smith Sphinx, all carved by one man.

America's first federal monument.

Scary metal statues adorn some of the signature buildings of Burlington, VT.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

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