This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

A river runs through this remote valley in a very unexpected way.

Hidden beneath a bridge, this waterfall is known for the large amounts of graffiti painted on its base.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

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

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

An enormous park-like oasis, full of famous Chicagoans' graves.

A 20-meter (65-foot) robot towers over Tokyo Bay.

A reproduction of earth's many biomes.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Rebuilt remains of a temple to Roman god Mithras.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A huge musical sculpture and other art installations on the National Oceanic and Atmospheric Administration grounds.

The magical, mossy forest that inspired Princess Mononoke.

The world's longest known cave system.

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

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

Crypt mausoleum in cathedral's basement contains relics of third century Roman martyr, Saint Vibiana.

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

A slice of central Asia in the middle of Berlin.

The ghostly remains of an accidental sea.

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

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

A toxic ghost town sitting atop a massive coal fire.