Once home to an aristocratic family and a workers' organization, this intricately tiled building now houses a chain restaurant.

In Coyoacán, a pair of coyotes crown a public fountain in reference to the ancient Aztec name of the borough.

This colossal ancient jaguar sculpture was used as a vessel for the hearts torn from sacrificial victims.

Many people don't realize there’s a lot going on in—and below—the world’s tallest triumphal arch.

The most complete statue of this Aztec god sits a top a throne carved with images of hallucinogenic plants.

This strange sculpture of a menacing skull surrounded by sun rays was discovered at the foot of the Pyramid of the Sun.

A museum in the former home of Marxist revolutionary Leon Trotsky.

The only castle in North America to ever house European sovereigns.

Frida Kahlo's childhood home, now a museum of her life and works.

An island filled with hundreds of hanging, decomposing, decapitated dolls.

The first permanent memorial to a unique secret weapon of World War II.

The massive, incredibly rare instrument is over 11 feet tall with a range so deep it goes lower than humans can hear.

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

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

This 18th-century sundial was designed to calculate the date of Easter each year.

This demon atop the Notre-Dame de Paris looks utterly bored.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

France's most famous cemetery, with some of its most curious tombs.

An early 20th-century bullring converted into a modern shopping center.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A giant chess set, minus the psychedelic drug trip.