Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

This small museum displays a collection of outsider art and scale models of past "treatments" for mental illness.

The remains of a enormous earthen figure of unknown origins cuts across a rural Wisconsin road.

A monumental underground karstic wonderland is also the water source for over a million citizens of Beirut.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

Because there's no place like home.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

Eastern zen meets Western grit in these four little trees growing out of a rock on Lake Tahoe’s Nevada shore.

Panoramic views of the city of New Haven and the Long Island Sound, with a side of history.

Chicago's North Park Village was once the largest municipal sanatorium in the country.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

The remains of this ancient fortress atop a manmade hill look as though they were built into a volcano.

If you've ever wanted to tear Hello Kitty apart with your teeth, this is the place.

An unfinished rail tunnel that has since been used to house cheese and bats.

This 19th century cyclorama acts like an analogue time machine to a different era.

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

This bridge was the birthplace of a unit of measurement based on a fraternity joke.

This fantastical and eclectic English garden takes its inspiration from Egypt, China, the occult and more.

Former military fort and site of untold horrors during WWII, this island may become the Adriatic's next luxury resort.

This Colorado hiking trail provides a small gold mine of abandoned gold mines.

One of Canada's most incredible rare book collections holds hundreds of thousands of gorgeous tomes that the general public can touch.