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

In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

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

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

Secret refuge and museum of the Duke of Florence.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

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

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

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

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

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Started as a kitchen garden, now the second largest botanical garden in the world.

The most visited, and possibly most controversial, museum in Germany.

Pyramid shaped monument with a tall tale attached.

Where Aleister Crowley attempted to seize the Hermetic Order of the Golden Dawn in a mask and a kilt.

Public access to clean drinking water was an instant hit among the masses.

Rebuilt remains of a temple to Roman god Mithras.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

This London plaque marks the spot where David Bowie's famous alien made his debut.