A wooden street sign is the last remnant of this 400-year-old alleyway.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

This giant subway sculpture celebrates the fruit that inspired the theory of gravity.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

The Swedish flag over this small naval fort signals that the nation is at peace.

Every Tuesday, students let off steam by screaming into the night air.

This fantastic cave remained unexplored until 1948 when three schoolboys discovered a hidden entrance.

This giant crucifix is like U2's Joshua Tree for Swedish death metal fans.

Stockholm's narrowest alley is barely over two feet wide.

Swedish skyscraper with a 90° twist.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

A man has revenged his true love's betrayal through tears and stone genitalia.

Early habitat dioramas and home of the elusive gaff, the skvader.

This chimerical bridge/tunnel appears to dead end right into the sea.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

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

Sweden's "good old days" painstakingly re-created in a model village.

This Stockholm light tower can be controlled by anyone with a smartphone.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

It houses the remains of a 17th-century version of the Titanic.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.