A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

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

France's most famous cemetery, with some of its most curious tombs.

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

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

At 207 feet, one of the world's longest continuous escalators.

The romance of early commercial flight still fills this Art Deco destination.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

A graveyard that dates back over 200 years stands near a busy shopping center.

Little has changed in the way that this mill operates since the 18th-century.

The Aldie Gristmill was once the largest factory of its kind in Loudoun County.

The only surviving 19th-century water-powered mill found in the Washington, D.C. area.

These unusual rooms on wheels are holdovers from the 1960s.

These massive concrete balls were used to mine gold in Virginia.