The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

Commonly acknowledged as the only public monument to the Devil himself.

A pair of gigantic baby heads greet passengers at Atocha Station.

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

This lucky bronze frog was gifted to Madrid by a casino.

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

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

Sometimes called the Banksy of Madrid, Muelle was a pioneer of street art in the Spanish city.

A lush indoor jungle fills this bustling Madrid transportation hub.

An abandoned airport in the middle of nowhere.

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

The world's largest wooden structure.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

A stubborn Ottoman tower with a punishing climb and a view over Eger

Take a hike to this unique rock formation formed by lava flows.

The largest statue of this convex, homogeneous object with just one stable and one unstable equilibrium point.

A 19th-century artistocrat's mansion, turned into a library, hidden in a modern library.

These seaside shelters once enjoyed by royalty remain a part of local history.

This mysterious chalk figure of a horse has been recreated and restored for more than a century.

A magnificent menagerie of oddities, including taxidermy cryptids.

The inverted pyramid design of this station stands out amid Bratislava's urban landscape.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.