This amazing pedestrian suspension bridge in the Swiss Alps would give Indiana Jones nightmares.

The alpine falls where Sherlock Holmes apparently met his demise can actually be visited.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

A historic observatory precariously perched at the "Top of Europe."

A cablecar-station-turned-revolving restaurant with 360-degree views of the Swiss skyline.

Caves famous for the dragon-slaying saint who lived there.

100 year tradition of fist fights, marked by marble footsteps.

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

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

Ancient ruins hidden underneath a modern luxury hotel.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

Rome's ancient Etruscan rival, now a park full of ruins.

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

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

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

A collection of objects supposedly singed by the hands of souls in purgatory.

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

Jesus' footprints and the first catacombs in the world.

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