This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.

The elliptical citadel resisted the advance of the mighty Ottomans several times, thanks to the military prowess of the "Dragon of Albania."

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

Something's watching you.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

This statue of a falling man commemorates a teenage martyr of the Hungarian Revolution.

Tucked away near more famous landmarks lies a statue meant to symbolize the confluence and continuing development of human culture.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

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

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A battle between nature and architecture in the Cambodian jungle.

Khmer Rouge's high security prison.

5,000 skulls in memorial to those killed by the Khmer Rouge.

Artifacts and memories from the Vietnam war, located in a place that experienced it first hand.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

A stunning silver lining to global warming's gloomy cloud.