Dictionary Johnson’s favorite feline.

The taxidermied remains of a once-great parrot.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

Notorious artist squat renovated into legal studios.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This long-hidden space above Westminster Abbey now displays the battle gear of the legendary King Henry V.

This one has sailed five times as far as Sir Francis Drake's famous ship.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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.

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

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

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

One of the smallest bookstores on the planet.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

A display of torture devices used in the Spanish Inquisition and other scourges of medieval Europe.

An ancient Egyptian temple in the middle of Madrid, Spain.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

A giant open-air sculpture made of over 200 full-sized boats.

A new sculpture calls attention to climate change in the centuries-old city it threatens.