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 mark of the Devil's horns on a marble column in Milan.

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

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.

A Milanese café entirely designed by the American director Wes Anderson.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

A space dedicated to contemporary art and culture, co-chaired by fashion icon Miuccia Prada.

The largest greenhouse in the world is home to over one million types of plants.

This Parisian gem is one of the most incredible ethnographic museums in the world.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This museum houses an imposing skeleton army comprised of creatures great and small.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

France's national museum of scientific and industrial instruments.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

A small part of Russia that does not touch any other part of Russia.

A unique form of erosion created an uncanny landscape of boulders perched atop slender columns of clay.

Five candy-colored villages on the Italian Riviera.

This former fascist summer camp was abandoned for decades.