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.

A beautiful geyser under environmental threat.

An architect's childhood fantasy treehouse made real.

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

One man's ambition created this psychedelic log home.

A legal loophole makes it possible to get away with murder within this 50-square-mile section of Yellowstone.

An apocalyptic seismic event creates a deadly chain reaction that ends with a 6-mile long lake developing within weeks.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

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

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

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

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

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

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

The only road through the heart of Glacier National Park.

The mountaintop wind turbine boasts a viewing deck — and a fair share of controversy.

This expansive bridge in the Canadian wilderness was originally just built for friends.

"Girl in a Wetsuit" is what happens when a sculptor has to find a way around a 100 year old copyright.

From mining complex to industrial exhibition, this museum once played a major part in the X-Files.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Limestone caves with spectacular showcase chambers.