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

Live a night as a Byzantine King, with a minibar and private jacuzzi.

A marvel of Byzantine engineering under the streets of Istanbul.

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

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

A huge cathedral single-handedly constructed by one eccentric monk.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Mine shafts and hard pastries await visitors at this massive mountain of salt.

The final resting place of the great navigator, or maybe his brother.

Commonly acknowledged as the only public monument to the Devil himself.

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

Cliffside houses provide a spectacular view from their perch above the valley.

Turntable anonymously received orphans, alms, and groceries.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

A beautiful but toxic fountain of mercury.

This cemetery features modernist statues as strange as its name.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Abandoned village in Sicily built during the agricultural reforms of Mussolini.