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

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

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

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Ancient snack bar of the Roman Empire re-opened.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

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

Pilgrimage site for star-crossed lovers.

Go inside to really appreciate this 500-year-old technological masterpiece.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Pompeii's less famous neighbor is still revealing her secrets.

The original Garfield station is the oldest station facility on the "L", with the station house dating from 1892.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

This memorial plaque remembers a strangely shallow maritime disaster known as "Chicago's Titanic."

A goddess-topped water fountain in Chicago was created thanks to the dreams of a thirsty newsboy.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.