When ecosystems collide in the arid Southwest.

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

The final resting place of many of New Jersey's most famous residents, including U.S. history's most in-vogue antagonist, Aaron Burr.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

The great American road trip, but smaller.

The first and only carousel with a lineup entirely of insects.

The Hudson River School comes alive at this palatial estate.

Discovered by cows, these upstate New York show caves are presented with a healthy dose of psychedelic folk art.

The only intersection in America where the buildings on all four corners were built pre-Revolutionary War.

A once grand hotel is being retaken by the wilderness it once capitalized on.

The world's largest kaleidoscope, designed by a 1960s psychedelic artist.

A glimpse into the lives of the the Miwok and Paiute people in Yosemite National Park.

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

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

"A hideous albatross in the Hudson River Valley."

The oldest continuously inhabited street in America.

This stone gatehouse was once the entrance to a historic mountain resort, and it had a cameo in a cheesy cult horror movie.

This throwback amusement park is home to rides and unique storybook figures from the past.

Why have you never heard of the second most popular tourist site in New York?

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

The abandoned ruins of America's first private zoo are open for exploration in the Catskills.

This Peruvian canyon is filled with geometric salt pools that have been being harvested since the Incan empire.