This symbol of the French Revolution still stands where it was first planted during the 18th-century.

A daring D-Day assault by U.S. Army Rangers is commemorated atop the high cliffs of this strategic point.

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

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

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

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

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A miniature train-ride through Slovenia's largest cave system.

The "dragon babies" of southeastern Europe.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This one-time health resort was used by aristocrats around the world.

A university observatory dome painted to resemble the beloved 'Star Wars' droid.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

This too-low North Carolina railroad trestle is still a notorious big rig executioner.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Theme park featuring miniature replicas of European monuments.

Climb inside an iron crystal magnified 165 billion times its normal size.

A little sculpture with a large wardrobe.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The oldest public library in Ireland.