The latest in a series of long glass bridges suspended at terrifying heights.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.

Why walk on this historical site when you can zoom down instead?

A temple to modernity, tucked away amid Barcelona's more well known museums.

The once highest point in China blends symbolic design with a kick of adrenaline.

A 30-acre garden inspired by the principles of modern physics.

One of Rome's most picturesque and original bridges was also a popular choice for Grand Tour artists.

This hidden alley near the location of Rome's first theater was the site of a curious miracle.

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

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

An alchemist's "magic door" stands in the middle of a Roman park.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

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

The final resting place of the poets Shelley and Keats.

The oldest operating pharmacy in the world features 800-year-old recipes.

2300-year-old Roman road connecting the empire.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The underground sanctuary of a mysterious ancient cult.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

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

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.