Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

An incarceration museum on the spot of possibly the oldest prison in England.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

An unusual, super-sized grocery adventure awaits in an Ohio suburb.

After a water tower painting was accused of being an ad, a simple fix was made that gave the city a motto.

Mussolini gave Cincinnati a bronze statue of Romulus and Remus suckling at a wolf's teats.

This monumental Jesus is often referred to as "Our Milk Carton With Arms."

This futuristically sylvan church is a glass-enclosed marvel of modern architecture.

This historic hotel on Bathhouse Row in Hot Springs National Park has a storied history of gangsters and baseball greats.

This quirky Arkansas wax museum does not shy away from the macabre and the grotesque.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Site of one of World War I's most horrific scenes.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

This striking fort on the Maginot Line looks just as it did after being destroyed in the Fall of France.

A towering baroque basilica jutting out of the French countryside.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

A former ironworks that was the first UNESCO industrial site.

The last bastion of Roman presence north of the Alps looms over a German town.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.