Rusting, graffiti-covered tanks litter the beach of this island, once used by the U.S. military for target practice.

The world's brightest bioluminescent bay.

An enchanting natural wonder in Puerto Rico's Camuy River Park.

This innocuous-seeming building is actually the remnant of a major wartime brothel.

This museum in a Paris apartment gives a unique look at the iconic French singer's life.

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

A modern-day Lascaux cave underneath Paris.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

The history of radiation is on safe display at the foot of a radiation science laboratory.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

This museum houses an imposing skeleton army comprised of creatures great and small.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

A surrealist timepiece by the artist of melting clocks.

A museum of magic with a Sadist past.