The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

The tombstone of an unfortunate explorer who disappeared in the Paris Catacombs.

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

A haunting collection of the vanished and disappearing natural world.

This massive library holds what was once the largest book collection in the world.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

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

This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

A surrealist timepiece by the artist of melting clocks.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

A meditative walk up 353 stairs leads to a majestic white Buddha overlooking Pai.

This extensive collection of dead bugs may be the world's most idiosyncratic and personal insect museum.

Buddha shrines hide within dark tunnels at this unique forest temple.

Thousands of bats stream out of caves every night on the edge on Thailand's second largest park.

The golden Buddha statue at the Wat Muang Monastery is the tallest in Thailand, and the ninth-tallest in the world.

Six times a day a train runs right through the middle of this Thai street market, sending vendors scrambling.

An enormous dragon scales the walls of this 17-story temple.

This museum has a most unusual location: inside a giant, three-headed elephant.

This dazzling Buddhist temple was constructed from over one million ceramic tiles salvaged from a British shipwreck.

Bangkok's men with dangerous jobs come here in search of protective talismans.

An on-site urban farm and fish pond supply some of the produce for this upscale restaurant.

An ancient system of freshwater caves filled with animal bones, including that of species long-extinct.

Founded during the Ayutthaya era, this unique Buddhist temple remains shipshape to this day.