2300-year-old Roman road connecting the empire.

Washington's iconic carousel has a nice piece of Civil Rights history.

Northern Ireland's Brobdingnagian stepping stones.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A bizarre roadside attraction and the first instance of miniature golf in the world.

This historic hotel invented the chocolate brownie.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

Baroque celebration of the end of the Great Plague of Vienna.

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

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

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

Hear the quietest sound from across the dome.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Two stone columns flank the grand Venice square, but there were supposed to be three.

The world's longest known cave system.

This distinctive Crescent City tradition dates back to the days of horse-drawn carriages.

A beautiful geyser under environmental threat.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

See massive fossils that are over 200 million years old in northeastern Arizona.