A beachside cave filled with Bronze Age metalwork, pottery, and human remains.

A series of caves, tunnels, and wells filled with fascinating figures and symbols.

A network of underground water channels that dates back to the Middle Ages.

An island on the Venetian Lagoon hosts this stone chair that has nothing to do with the King of the Huns.

Nine caves filled with recently-discovered archaeological finds under the houses and the streets of the most ancient district of an old town.

This church houses the tomb—but not the remains—of St. Nicholas, the likely progenitor to Santa Claus.

Legend says this sacred tree was a gift from goddess Athena.

It's said that at this location, a Scottish poet met the Queen of the Fairies.

One of the most successful gold mines of the Victorian gold rush.

An improbable waterfall springs from an orange-white cliff face, tumbling into the headwaters of the Virgin River above Zion National Park.

The classic Christmas carol was written at this Massachusetts tavern in 1850.

Hidden in this modern shopping center is a relic of 16th-century capital punishment.

This Roman underground canal was the longest tunnel ever built until the late 19th-century.

These World War I shooting range tunnels are now haunted halls of underground graffiti accessed through the roots of a tree.

The world's first motel is now an administrative building for an apple farm.

One of the first commercially successful anthracite-powered iron-making operations in North America.

This crumbling coast and its teetering tower are literally filled with history, but they are also at great risk of becoming history themselves.

Found in the waddenzee, this propeller has been put on public display as a reminder of the Second World War.

A marvel of Byzantine engineering under the streets of Istanbul.

A high school astronomy enthusiast designed this model of our solar system to be traversed on foot.

While not recognized by Guinness, this chocolate waterfall is likely to be the world's largest.

This abandoned mine offers a glimpse at what life was like for those who came to Alaska seeking Gold Rush riches.

Parts of this former military training ground may have inspired parts of J.R.R. Tolkien's famous fantasy series.

This archaeological site built into a tuff outcrop is filled with rock dwellings, the ruins of a medieval castle, and a necropolis.