A marvel of Byzantine engineering under the streets of Istanbul.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

The taxidermied remains of a once-great parrot.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

As the Dead Sea continues to deplete, massive sinkholes open along its banks.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

An ancient capital city that dates back 3,000 years and harbors many surprises.

Charnel house at the foot of Mount Sinai.

An alien landscape of chalk-rock in the Egyptian desert.

This bazaar is one of the oldest in the Arabian world.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

This indoor ski resort has a mountain contained inside a mall.

Whitewashed mosque contains the world's largest carpet.

Feed it cash, get your very own gold bar.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

A local prank turned town icon.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

A painfully obvious spy house sits right across the street from the Russian Embassy.