An abused and forgotten metropolis, abandoned for centuries.

This famous city eluded concrete detection until the early 2000's.

Roman ruins top white travertine terraces formed by ancient hot springs.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

This giant volcanic crater holds its very own field of salt.

Village of slate houses, built on a white marble outcrop.

More than 100 monumental tombs carved into rock are preserved at this ancient Nabataean site in the Arabian Desert.

An unfinished tomb carved into a giant boulder in the Arabian Desert.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The oldest and smallest cemetery in Paris is only open to the public twice a year.

With a history of slaughter, feast, and famine, remnants of the pork industry decorate this area--even its church.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

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

This Paris art space celebrates the creativity and ingenuity that springs from abject poverty, especially in Africa.

A modern-day Lascaux cave underneath Paris.

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

This Parisian café sticks almost exclusively to an ethos of reuse.

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.

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

A surrealist timepiece by the artist of melting clocks.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.