A local dialect born in the late 19th century is only spoken in this isolated California valley.

Ride the subways of yesteryear.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

An acoustic anomaly with a mysterious cause.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

The largest self-built castle in the U.S., six decades in the making.

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

A museum dedicated to the alleged Roswell Incident.

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

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

The world's longest known cave system.

Experience park where visitors are told to expect the unexpected.

A floating cat sanctuary on an Amsterdam canal.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

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

This massive wooden building contains a giant Buddha, healing pillars, and tame deer wandering the grounds.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.