For one day every month Barcelona's Estació de França transforms into a market for model trains.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Mountain where Jesus was first tempted by the Devil.

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

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

The world's only museum devoted to the wonders of fluorescence.

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

This hidden art nouveau gem was designed by an architect in search of a national style.

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

Sitting beneath an unremarkable residential building is a museum devoted to classic Pinball.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

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

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

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

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

A modern sliver of architecture in Roma.

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Architectureal fantasy quarter of Rome.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.