The original burial place of this preeminent 18th-century Jewish philosopher was razed by the Nazis.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

The world's first motorway was used as a racetrack until the late 1990s.

A statue of an astronomer gazes at the sky as a tribute to Caroline Herschel.

A socialist building dedicated to teachers showcases one of the largest Soviet mosaics in the world.

After local authorities changed the design, the building's architect, Le Corbusier, wanted nothing to do with it.

This public observatory is home to the "celestial cannon," the longest pointable telescope in the world.

The oldest stone house in Paris was built by its most famous alchemist.

The camera-toting gargoyle juts out from the exterior of a Gothic cathedral.

This impressive former palace contains a hidden gem for fans of modern sculpture.

This haunting location was featured in the final scene of a classic spaghetti western.

Head to the mountains to catch a glimpse of Spain's endangered subspecies of brown bear.

The current seat of the Parliament of Andalusia was once the epicenter of the Great Plague of Seville.

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

Now a pile of ruins and rubble, this was a lovely mountain town as recently as 1960.

An abandoned Indian-inspired mansion.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

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

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.