The medieval castle built as headquarters for the Pope's secretive Knights Templar.

The heart of a Scottish legend had a centuries-long journey before reaching its final resting place.

One of the last remnants of the Bessemer process that revolutionized steel production during the industrial age.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

An Anglo-Saxon cross inscribed with possibly the oldest written work of English literature.

This artificial archipelago was supposed to resemble a map of the world.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

Whitewashed mosque contains the world's largest carpet.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

The world’s largest LED display, built over an F1 race circuit.

This enormous sports car themed amusement park is home to the world’s fastest roller coaster.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

A hundred copies of Antony Gormley's naked body stare out across the water.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

This elaborate towering structure was once famed for its revolutionary height.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

A stone copper was sculpted on the wall of the Carlisle Cathedral to honor a local hero.

Displaced highlanders would take shelter from the wet Scottish climate under the large walled bridge at Glasgow Central Station.

A small island abbey is the final resting place of many medieval Scottish monarchs, including the real Macbeth.