The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Macabre astrological automaton clock dating to the late 1400s.

One of the most controversial statues in Romania is an emperor with no clothes.

Romania's triumphal arch looks out over Bucharest.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

The first skyscraper to include a Ferris wheel built into the facade.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

Underground monastery and fortress.

The most visited pilgrimage site in Armenia once held a saint in a pit for 13 years.

A cluster of headless, armless sculptures looms within a popular Polish park.

The most famous location in China was home to whole dynasties worth of imperial rulers.

Sacred Indian temple that’s all monkey business.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

The 953 windows undoubtedly make this the world's most beautiful screened porch.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

These mechanical goats first battled it out in the year 1551, all because of an overcooked deer.

The history and future of cannabis.

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

Elaborate tile work in this railway station tells the story of Portugal.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

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