Apartment complexes built into huge repurposed natural gas tanks.

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

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

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

An exquisite Baroque church in Vienna's old town.

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

The beautiful baroque library of the Hapsburg empire.

The bright red cars take travelers through breathtaking Tuscan scenery.

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.

More than 450 years ago, an Italian nun became the first woman to paint the iconic subject.

The middle finger of modernity.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

Breathtaking and huge 430 year old maps of Italy.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

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

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

This subterranean shrine beneath a bike rental store celebrates the iconic Italian scooter.

An ancient Egyptian obelisk is now used to commemorate fallen Italian soldiers.

Ancient ruins hidden underneath a modern luxury hotel.