The walls of these four caverns are filled with art that dates back to the earliest human presence in Europe.

Seventy-five miles of limestone caves host more than a million bottles of wine beneath a sleepy Moldovan town.

An underground nightclub helped spark a "Singing Revolution."

The summer residence of a Spanish ambassador who brought viticulture to an impoverished region, sparking its transformation into one of the world's best wine regions.

Dive for drinks at Croatia's first and only underwater winery.

The oldest surviving wooden bridge over Rhine lets travelers cross easily from Switzerland to Liechtensten.

In one of the world's smallest countries, a royal's personal winery is open to the public.

Obscure Freemasons still live in D.C.’s largest private residence.

Largest Roman Catholic church in North America.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

The final resting place of two (or three) presidents, one vampire, and 18,000 Confederate soldiers.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

Inside this magical collection, you can buy recipes cooked up by church ladies, motorcycle clubs, and clowns.

A maze of underground tunnels beneath one of the most beautiful forts in Serbia.

The Route 66 institution that inspired Taco Bell also served as an important headquarters for Mexican-American social movements.

A little theme park full of miniature monasteries and churches, made by hand.

This 15th-century Serbian Orthodox monastery also contained a school for illuminating manuscripts.

Legends of treasure and spirits flow from this this fairy tale-like oasis.

This rare and ancient Christian relic is one of Ireland’s oldest freestanding stone crosses.

A striped 12th-century basilica sits in the countryside of Sardinia.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This historic estate on the east shore of Lake Tahoe was home to an eccentric millionaire (and his pet elephant, Mingo).