Small on the outside, big on the inside, this church is an astonishing act of visual deception.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

Pompeii's less famous neighbor is still revealing her secrets.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

A two-way chairlift system between Zugliget and the highest point in the city.

A miniature train-ride through Slovenia's largest cave system.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

The romantic garden was the epicenter of the Hungarian art scene in the 1880s.

Once the home of a hermetic monk, this cave now houses a small church.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Op-art architecture designed for happiness.

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

A patriotic medieval knight in driven-nail armor raised money for widows and orphans of WWI.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

A neo-Gothic mansion now houses a wunderkammer of analog tech that hits on all the senses.

Apartment complexes built into huge repurposed natural gas tanks.

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

Legends surround an ancient tree trunk riddled with nails for good luck.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.

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

The abandoned funicular tunnel was a secret base for the BBC during World War II.

Made famous by 'Star Wars,' these troglodyte homes face an uncertain future.