In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

Real bones which are said to have belonged to a Polish dragon.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A whimsical bridge adorned with decorative dragons.

The celebrated eyesore created by starry-eyed sweethearts.

A French artist's vague warning hangs over Belleville.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The house that took a plunge into the facade of a museum.

The topiary maze at the Habsburg hunting lodge.

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

Stunning Roman aqueduct used for 1900 years and still standing.

The effect of this ancient form of image projection situated atop an 11th century Moorish palace is thrilling.

A complimentary beverage is offered to the bodega's resident rodents every day.

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.

The townhouse where the English poet created some of his most influential work has been preserved in tribute.

This hidden green space is the city's second largest conservatory.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

Cold war icon and onetime "hole" in the iron curtain.

One of downtown Berlin's last reminders of its Communist past.

From Iggy Pop to David Bowie to Nick Cave, this regal music studio has served some of the all time greats.