This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

The middle finger of modernity.

One of America's oldest private membership libraries was long one of New Haven's best kept secrets.

Mosaics, storks, and brothels—this ancient city has it all.

Over 3km of caverns and caves at the Switzerland-France border contain the largest underground river in Central Europe.

The largest source of fossilized insects anywhere.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

This cave holds a surprisingly colorful variety of geological oddities.

Deep scars on the earth left by the Ice Age.

A real flying saucer, contracted by the U.S. Air Force.

Remnants of 19th century vigilante justice.

The blood-soaked ruins of the castle where the murderous Blood Countess was walled in alive.

An isolated village literally built into the crevices and rock formations of a mountain.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

Stalactites and stalagmites in a beautifully lit cave.

Ancient paintings known as the "Sistine Chapel of Cave Art."

15,000 year old bison sculptures.

An archeological treasure trove stumbled upon by a couple of children.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

Small shop offering mail-order rare and exotic plants.

Stumps of an Ice Age forest, visible only at low tide.

America's oldest archaeological site or a muddled case of wishful thinking.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.