An exquisite tunnel of cascading flowers.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A terrific purveyor of natural history objects and curios.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

A huge musical instrument played by the ocean.

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

This huge abandoned fortress hidden inside a mountain holds a world of subterranean secrets.

Lady Liberty's original designer installed a little clone in this French fountain.

The world's largest reflecting pool is just two centimeters deep.

The eclectic observatory castle of a 19th-century astronomer and explorer.

This Bordeaux parking garage has 712 indoor spaces, and one outdoor.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

Abandoned blockhouses from Nazi Germany's Atlantic Wall erode into the sea on a French beach.

Winston Churchill painted this lake during his stay Woolsack Castle in the Landes forest.

This medieval chapel is now a shrine to the region's favorite sport.

Abandoned Nazi train station turned underground astroparticle laboratory.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.