Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

This delightful little museum is dedicated to only one thing: pasta.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

A fairy tale castle in modern Rome.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

An alchemist's "magic door" stands in the middle of a Roman park.

Architectureal fantasy quarter of Rome.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The small peaceful island off the Venice tourist circuit is where the city began more than 1,500 years ago.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

Walk through Czech history in Prague's largest graveyard.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Antique frame collection with 2,400 frames.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.