This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

An effigy of a trapped paratrooper dangles from a Normandy church to commemorate one remarkable D-Day event.

This crack in France's seaside cliffs once hid a sinister secret.

Former bridge turned into an observation tower.

Walk through living pictures and music in the Cathedral of Images.

This ancient theater was once the home of fierce gladiatorial battles.

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

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Historic medieval fortified city in southwest France.

At the foot of an active volcano sits a church miraculously spared by its lava.

On one of the world's most active volcanoes, a pebble-filled crater changes color with the wind.

At the center of an island in the middle of the Indian Ocean is a deep chasm ringed by tall waterfalls.

Réunion Island's highest point is a 2 million-year-old volcano and a paraglider's paradise.

This giant sculpture made of trash is a critique of society's wastefulness.

A beautiful but toxic fountain of mercury.

A beautiful little museum hidden away in the heart of Barcelona holds a treasure trove of Ancient Egyptian artifacts

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

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

Buddha and Jesus tower over this French mountainside headquarters of the Aumism religious cult.

A fortress on this island housed the mysterious prisoner known as the "Man in the Iron Mask" for more than a decade.

The ruins stand as a somber reminder of France’s worst civil catastrophe of the 20th century.

This mosque was based on Sub-Saharan Islamic architecture and created for the Senegalese Tirailleurs.