One of the few working locomotive roundhouses in the United States.

The only surviving prototype for Buckminster Fuller's house of the future.

The medieval center of the Islamic world was also once the seat of Saladin's sultanate.

Slum Settlement Filled With Mountains of Garbage.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

A local student's chance encounter with Keith Haring led to the creation of one of Europe's largest murals.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

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

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

Breathtaking and huge 430 year old maps of Italy.

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

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

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

The middle finger of modernity.

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

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

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

Its interior is adorned with some of the best examples of early Christian mosaics.

This large, circular tomb is the final resting place of the first emperor of Rome.

A large replica of a monumental Roman inscription is located on the side of this museum.

Rome's first modern graffito is all that is left of a peaceful protest from the 1970s.