The world's longest tunnel with an undersea section.

This bridge was constructed from the rubble of the infamous Bastille.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Medicinal spa created with the discharge from a geothermal energy plant.

A tiny chapel clings to a precipice above Germany’s gemstone capital.

The stones of this formerly witch-obsessed castle were used to build a church.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

The birthplace of the ferocious William the Conqueror, this castle is awash in medieval history.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

Folklore and history carved into Brittany's coast.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

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

A quaint medieval millhouse hovers surprisingly above the waters of the Seine.

Two small chapels housed inside an ancient tree.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

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

The humble tomb of an Argentine general, hand-built by his son using stones brought down from the Andes.

A beautiful young girl said to have been buried alive in her coffin…

A tower devoted to — and modeled after — the Divine Comedy.

This historic, palatial theater is now one of the world’s most beautiful bookstores.

An abandoned whaling station on an active volcano offers hot springs in Antarctica, surrounded by ruined giants of industry.