A forgotten "city of water" underneath the famous Trevi district.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

The “Coin Cabinet of Dresden” houses a collection of over 300,000 numismatic artifacts, one of the largest of its kind in Europe.

The largest treasure hoard in Europe is contained in a castle that was bombed out during World War II.

An otherworldly, fossil-rich cobble beach holds Viking graves, cairns, and other remains.

A medieval cave used to shelter local hermits now holds nearly 200 old Quaker gravestones.

Ancient, mysterious stone altars are hidden among wild woods in central Italy.

This ancient Irish landscape boasts hundreds of legendary ruins.

The world's only official college program focused on "clown therapy."

It took a lifetime to collect these mechanical musical wonders.

A sprawling ancient Jewish cemetery with over 30 rock-hewn burial caves.

The tallest waterfall in the Judean Desert is named for its connection to a biblical figure.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

A remote island settlement off the coast of Tanzania is a storied archaeological site with an ancient past.

Sitting atop a rock on Michamvi Pingwe beach, this restaurant becomes its own island at high tide.

This sacred, circular cave is lined with pools so clear and still that it's hard to tell where the water begins.

Stunning ruins of what was once the center of one of the greatest empires in East Africa.

Mosques carved from coral and dozens of well-preserved stone structures fill this 500-year-old Swahili trading center.

Colin Stokes "got a bit carried away" and built a castle that looks like something out of Tolkien.

Abandoned railway line circling the city of Paris.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

This huge pile of volcanic boulders hides a stunning network of secret grottoes.