Former headquarters of the KGB.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

This softball diamond has a culture all its own.

This museum houses two of Mexico's most impressive Aztec monoliths.

This stunning and ethereal mural symbolizes the beauty, unity, and diversity of humankind.

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

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

The striking jade death mask of an ancient Maya king is displayed in a replica tomb in Mexico City.

On a cornerstone of the City Museum is the head of a monstrous serpent stolen from an Aztec pyramid 400 years ago.

This incredible college library is a visual masterpiece of mosaic art. It also looks kind of like a giant boombox.

Mexico City's largest market contains a Willy Wonka-esque wonderland.

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

These haunting ruins of a 700-year-old Prehispanic city have witnessed centuries of wars and massacres.

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

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

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

Budapest's Communist-era statues, banished to the suburbs.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Museum dedicated to the terror regimes of Hungary.

A toxic ghost town sitting atop a massive coal fire.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.

A lone tower rises above the cliffs in a city park, offering fantastic views of the Connecticut landscape.

This exhibit is one of the largest and most well-preserved collections of Jurassic-era trackways in the United States.