The intricate geometry inside this Baroque-style dome was designed to create "terror of the human soul."

An island on the Venetian Lagoon hosts this stone chair that has nothing to do with the King of the Huns.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

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

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

This "floating railway" is one of the world's oldest monorail systems.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The fairy tale castle of the "fairy-tale king."

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The narrowest street in Paris.

A quaint medieval millhouse hovers surprisingly above the waters of the Seine.

This bridge was constructed from the rubble of the infamous Bastille.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.