Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

This abandoned Belgian fortress is purposefully being left to nature.

A luxury hotel housed in a former 15th century Gothic church.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Breathtaking and huge 430 year old maps of Italy.

Apartment complexes built into huge repurposed natural gas tanks.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A spherical "micro-nation" in the heart of Vienna.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Op-art architecture designed for happiness.

Baroque celebration of the end of the Great Plague of Vienna.

The world's most active stratovolcano is almost always erupting.

A German town is growing a building out of trees.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Mountain where Jesus was first tempted by the Devil.

This abandoned church in central Lyon is missing its front stairs.

Lyon's "Wall of the Silk Weavers" is one of the largest murals in Europe.

A meteorite-bounded town in Bavaria.

An elevator into the Baltic Sea.

This famed marionette theater and museum is bursting with imaginative string puppets.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.