This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

This geothermal hot spring hides beneath a slowly growing mineral dome.

This frequently-photographed waterfall takes only a short hike to visit.

Towering basalt columns, a creation of fire and ice.

Take a drunken tour inside the world's largest known geode.

This naturally-sourced hot spring is now home to a clothing-optional resort.

An underwater city for the dead.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

Where manatees are the snowbird vacationers in these balmy Florida springs.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

The rocks in this arid basin leave trails of movement behind them.

A beautiful geyser under environmental threat.

This abandoned amusement park was built on a site with a dark history.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

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

Mysterious rocks that ring musically when struck.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

The United States Capitol's former columns still stand.

A toxic ghost town sitting atop a massive coal fire.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

Enormous lake at the bottom of a unique cave system.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.