Shimmering sea-colored mosaics and Jesus statues cover this opulent building.

Naturally formed rock city in Poland.

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

This 8th-century Bavarian monastery is home to an exquisite Baroque-era library.

The oldest hydroelectric plant in Czechia is now a museum.

Be(w)ar(e) the moat around this historic Czech castle.

The mystery of the Putim Ossuary involves a tricorn hat.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

Massive installation of Europe's negative stereotypes.

The cave holds a spectacular array of stalactites and stalagmites, including one shaped like a giant human heart.

The last standing example of an ancient district's teatime tradition.

This architecturally eclectic fortress witnessed centuries of bloody turmoil, including the massacre of its ruling clan.

The secret room where early Bolsheviks cranked out propaganda fliers on a smuggled printing press.