The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

Sofia's legislative center is continuously reinventing itself.

"Holy Wisdom" overlooks the city that became its namesake.

A vast Communist-era exhibition space in the Bulgarian capital.

A striking symbol of the Bulgarian capital.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

Now a memorial, this factory was once used as a concentration camp for artists by the Vichy government.

A unique underground structure dating back to the 1st century BC.

This ancient theater was once the home of fierce gladiatorial battles.

A surrealist timepiece by the artist of melting clocks.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Notorious artist squat renovated into legal studios.

Modern pyramids built to channel positive energy have also fomented local tales of animal sacrifice.

Secret refuge and museum of the Duke of Florence.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.