The ornate miniature mansions were built for Istanbul's feathered residents.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

A deadly ancient portal to the underworld.

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

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

A Belle Epoque bordello turned into a themed love hotel.

Inside a former cabaret, seven floors of erotic art.

One of the last umbrella repair shops in Paris upholds the nostalgic art of umbrella making.

A glamorous hotel that once accommodated French resistance fighters and concentration camp survivors.

A Parisian boutique devoted to la Sape, the elegant Congolese fashion subculture rooted in European colonization.

Stripes of human ashes cover a back lawn in the most sought-after burial grounds in Paris.

A simple plaque on the facade is the only reminder that the treaty ending the American Revolution was signed inside.

What looks like a normal building is really a hollow facade hiding a subway vent.

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

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

This little-known relic crypt holds stolen parts of a Roman Empress.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

BDSM, 1930s Style.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

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

A series of abstract, silly sculptures represent the works of a great modern classical composer.