An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

Home of Philip Johnson, one of the 20th century's most influential architects.

This luxury hotel suite is located deep in the bowels of an old mine.

Hollowed out cedar log tubs set in an ancient towering forest.

A darkly erotic open-air statuary in Catalonia.

Medieval village and microminiature museum.

Of course Salvador Dalí lived in a castle...

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Chicago's museum dedicated to the history of bondage and fetishism is more textbook than titillation.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

This striking public art installation is suspended above a public park, designed to gently move in the breeze.

Its founder calls it a "proletariat art renaissance".

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

Private collection of art inspired by cabinets of curiosity.

Humboldt's human-powered sculptures race across land and sea for days on end in a wacky quest for dominance.

Historic marionette theater features thousands of handmade puppets and free cups of ice cream.

Museum dedicated to the struggles of the disabled.

A natural gas leak provides a flickering flame beneath a waterfall.