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

Fantastic stories on a miniature railroad.

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

Double spiral staircases are not unheard of, but they are very rare.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

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

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

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

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

Where the lovelorn find a home for their sentimental keepsakes.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

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.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The oldest operating pharmacy in the world features 800-year-old recipes.

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

The secret medieval communication system will whisk your words above the noise of the crowd.

These paved rills bring freshwater into Altstadt and could spell wedding bells for whoever stumbles into the waters.

This sculpture honors the man who was known as the "Righteous Among the Nations."

Museum dedicated to the terror regimes of Hungary.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This strange statue features a bust of the famous composer plopped atop a woman's body.

A small marionette collection located within the dark cellars of an 11th-century Austrian castle.