One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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

The world's only museum devoted to the wonders of fluorescence.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

The attic of a four-century-old canal house hides a clandestine church.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The morbid items in this small and hidden museum are not for the weak stomached.

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

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

A bookstore dedicated to the intersection of comedy and art.

For one day every month Barcelona's Estació de França transforms into a market for model trains.

Mountain where Jesus was first tempted by the Devil.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

This abandoned subway station can still be seen on regular commuter trips.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

The famous author's cottage hideaway.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

A journey begins with a single step, and for many, the road-trip of a lifetime started at this Chicago intersection.

A Chicago Movie Palace Lost to Time.

A small Chicago museum filled with thousands of preserved butterflies, beetles, and more.

Small and slightly hidden, the American Writers Museum is preserving the legacy of America's finest authors.

Those belting out show tunes might not realize this piano bar marks the site where Thomas Paine died in 1809.