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

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

Living towers made of people that are now recognized by UNESCO.

A unique collection of military history dating back to the American Revolution.

Hidden behind a wall, Spanish nuns distribute their signature sweets on a revolving tray.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

A 16th-century Andalusian palace.

An eerie collection of the surviving structures from a past celebration of the future.

The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

Red, white, and blue painted steps along with a Union Jack celebrate the outcome of Gibraltar's 1967 referendum.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

The discovery of these rare, ancient artifacts led to the creation of a new museum.

The world's most elegant power lines.

A Spanish town built into the cliffs.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

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

You can spot this teeny tiny stained-glass window from the Bonifacius bridge.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

An artificial date palm stands as a memorial to Warsaw's Jewish community.

These plaques found across Warsaw commemorate the sites where executions or battles took place during the German occupation.

This colorful and quirky set of pegasus sculptures celebrate the works of poet Zbigniew Herbert.

This bell stars in a tragic love tale and is said to make wishes come true.

Legend says this is actually a heartbroken prince waiting for his true love's kiss.