An eerie, derelict amusement park in Berlin.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

Looming communist pillar with a Czech twist.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Macabre astrological automaton clock dating to the late 1400s.

A peculiar clock commemorates a historic victory won by ringing the noonday bell an hour early.

Europe's second largest ossuary wasn't discovered until 2001.

Op-art architecture designed for happiness.

Austria's ultra-modern art museum looks like Cthulhu's giant alien heart.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.

A relic from the Industrial Revolution got a second life as a contemporary performing arts space.

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

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

Go inside to really appreciate this 500-year-old technological masterpiece.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

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

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

An abandoned Byzantine fortress and notorious prison.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Ancient snack bar of the Roman Empire re-opened.