While the U.S. and Soviet Union were engaged in a space race, Poland built a UFO on the ground.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

The silly symbol for an underground protest group is now scattered around the city.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

An underground city of salt.

Tourists often confuse this beautifully ornate former cigarette factory for a mosque.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Time has been frozen at this station since the bombing in 1980—or so it was believed.

Three underground crypts and a pointed arch under the bell tower make this cathedral unique among Romanesque churches.

Nobles would stage mock naval battles on this large lake at the Royal Palace of Caserta.

This castle was once the home of one of the most powerful women of the Renaissance.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

A long-buried ancient ruin unearthed right in the middle of the city.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

The oldest volcanology research center in the world.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

A 1,000-year-old church holds the bones of the Christian martyrs who died hiding inside it.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Southern Italy's spinning top village.