A medieval military street hidden beneath a charming French fishing village.

Artist's eccentric property excessively decorated with found objects and work of his own.

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

This massive blockhead sculpture hides an entire library.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

What if all public housing projects had been designed by "the Pygmalion of modern architecture," not only their prototype?

For a brief time in 1960s France, families could climb into a tiny submarine and be pulled along an underwater journey.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

Immortalized by artists, this church incorporates a medieval lighthouse into its shoreside structure.

Long tunnels run under the ancient chariot racing circuit to the tower.

Stunning Roman aqueduct used for 1900 years and still standing.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Turntable anonymously received orphans, alms, and groceries.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

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

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

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

A landmark in the history of technology and computing is hidden in a tiny Baroque chapel.

This building has a giant piercing through one of its corners.

Legend says these stone structures are where the doomed citizens of a vanished village sent themselves to die.