Stockholm's deepest subway station is also a stunning ecological wonder.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

This unattributed sculpture in Amsterdam is hiding in plain sight.

A floating cat sanctuary on an Amsterdam canal.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

This store decorated with Japanese and underground pop culture items has been the centre of Barcelona alternative fashion scenes for more than a decade.

Self-sufficient greenhouse floating on the Hudson River.

This crumbling Art Deco movie palace in Mexico City has been abandoned for two decades.

One of the last mosaic tile facades found in the city.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

Decades before the scandal, this staircase on the river was a literal "water gate."

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.