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

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

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

During the Soviet era, the spire of this longstanding church was used as a radio transmission tower.

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

This church also serves as a lighthouse complete with a beacon.

These enormous, stern-faced statues greet visitors with lanterns, and sometimes costumes.

An abstract monument to a symphonic composer.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

A subterranean house of worship carved right out of the bedrock.

A bronze statue of the fictional character nicknamed "Mrs. Hat" from a beloved Belgian comedy.

You can spot this teeny tiny stained-glass window from the Bonifacius bridge.

These towering cliffs jut dramatically from the middle of a barren desert.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

An exhibition devoted to the life (and posthumous taxidermy form) of the last known representative of the Pinta Island Tortoises.

Brightly colored 30-foot-tall totems light up the desert sky just outside Las Vegas.

Visit the monolithic tomb of America's most famous general.

On the walking path from Monterosso to Vernazza, a small shrine dedicated to feline friends.

Most historians agree that the so-called "Gentleman Pirate" wasn't much of either of those things.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

The ruins of a sixth-century monastery sit on the banks of the River Shannon.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

Kakadu National Park is known for its stunning beauty and its rock art, which represents the longest historical records of any continuous civilization on Earth.

The third-tallest lighthouse in the United States stands as a reminder of Atlantic City's early days.