Valletta’s outdoor theatre stands within the ruins of a 19th-century opera house.

This unique building in the main square stands out among the city's typically Baroque architecture.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

These erosion formations on the wave cut platform have a natural explanation

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

A whimsical bridge uses saxophones to pay tribute to two great men and the European Union.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

Abandoned Nazi train station turned underground astroparticle laboratory.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

Beneath the city of Lourdes, France is a massive, concrete church.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

The site of the first medieval crusade that pitted Christians against Christians.

Historic medieval fortified city in southwest France.

This feat of diesel-powered engineering enabled boats to bypass a series of five locks.

Built to hold the worst of the worst of the Nazi war prisoners.

This pyramid is dedicated to all those who suffered martyrdom for civil and religious liberty in Scotland.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

Bell tower juts out from a village buried under a lake.

This winding road through an Italian canyon may be the most scenic drive in the world.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Go inside to really appreciate this 500-year-old technological masterpiece.

Two stone columns flank the grand Venice square, but there were supposed to be three.

The only museum with its curator—and her pets—buried inside.