A restaurant and observation deck built in a unique broadcasting antenna.

A unique Holocaust memorial tells the personal stories of the Jewish residents exiled from greater Berlin.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

A once-secret library of Freemason history in Catalonia.

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

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

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.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

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

Mountain where Jesus was first tempted by the Devil.

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

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.