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.

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

The world's tallest palm trees look like the whimsical kind of plant you'd find in a Dr. Seuss story.

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

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

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The former estate of the Guggenheims, part of the opulent Gold Coast that inspired the Great Gatsby.

The abandoned grounds and derelict greenhouses of this once-magnificent Edwardian estate are now a nature preserve open for exploration.

An abandoned Gold Coast-era mansion once intended for the exiled ruler of Albania, who never arrived.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

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

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