One of the best places to dig—some say on the planet—for six different types of chalcedony.

A little-known caravanserai hidden among farmhouses in the Turkish countryside.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

Western New York's largest independent bookstore doubles as a historical repository of all things Niagara Falls.

The house where the pulp fiction writer and Conan the Barbarian creator lived.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

A well-worn marker in a forgotten alleyway is all that remains of what had been one of Manhattan's most beautiful buildings.

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

The walls of the iconic dome are hollow and have a secret stairway.

A wondrous old library overlooking the nation's capital.

Britain’s longest ancient monument, this great 8th century earthwork was built to mark the boundary between what would become England and Wales.

A nostalgic bibliographic gem.

A historic ruin just 20 feet away from a busy highway onramp.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

Standing proud atop a Turkish bluff, this Ottoman palace has retained its grandeur despite being abandoned for centuries.