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

Paris' linguistic guide to the international language of, yes, love.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The oldest stone house in Paris was built by its most famous alchemist.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An eccentric millionaire's personal curio collection includes at least one shrunken head.

This railroad magnate's 19th century tower is more than a little bit out of place in the Nevada desert.

This central Nevada cave is the spiritual home of ancient and enigmatic pictographs.

Only intact Ichthyosaur skeleton in the United States.

This tiny cluster of abandoned buildings looks like the future of the ghost town - today!

This famous Nevada gold mine, once a hotbed of Wild West shenanigans, is now open for tours.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

A seven-century-old jail tells a not-so-pleasant history of crime and punishment.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

A rare tour of an aristocrat's private home reveals valuable 17th-century paintings from artists like Rembrandt.

This basement museum explores the art and artistry of fascism.

A former plague hospital turned medical museum.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The attic of a four-century-old canal house hides a clandestine church.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.