In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

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

Sitting in the basement of a castle, the largest wine barrel in the world is bigger than most apartments.

Every day is like Christmas on this street where the traditional Neapolitan nativity scene comes to life.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

This medieval city gate is now a blend of the past and the modern world.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

This magical-looking island is notorious for the misfortunes suffered by its owners.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

According to the legend, this structure was built in a single night with the help of the devil.

Amalfi's pre-industrial history is slowly being engulfed by the lush vegetation of the Ferriere Valley.

The entrance to this Frankfurt subway station looks like an old tram car crashed into the concrete sidewalk.

At this ancient settlement at the foot of Mount Babadağ, honeycomb tombs are carved into a round cliff.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

More gold than anywhere else, ever.

Known locally as "the giant head," this 14-foot LED sculpture has a photo booth in the neck where you can have a 3D picture taken and displayed.

This historic little railroad runs through some of the most beautiful scenery in Germany.

A historic steam train meanders along one of the most scenic rail routes in Germany's Black Forest.

This everlasting lightning storm may be the world's largest generator of ozone.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

The world's oldest individual clonal tree looks like a wimp despite standing tall for 9,550 years.

One of several Lilliputian portals that are ready to transport passengers to other dimensions, if they can find them.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

This full-sized orange tree lives suspended in mid-air above the streets of Jaffa.