The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

Next to the Leaning Tower of Pisa is a cemetery home to ancient sarcophagi and disturbing murals.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Two stone columns flank the grand Venice square, but there were supposed to be three.

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

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.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

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

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 remains of this 2nd-century Roman temple are incorporated into a modern building.

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

This curious, round temple is the oldest still-standing marble building in Rome.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This ancient market is often referred to as the oldest shopping mall in the world.

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

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Ancient ruins hidden underneath a modern luxury hotel.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.