Ecuador's largest Incan ruins show evidence of sophisticated irrigation and diplomacy among the ancient builders.

This legendary city has been a tourist attraction for centuries.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

The quintessential Japanese rock garden has existed for more than 500 years.

This narrow path was cut right into a French mountainside to feed the country's early naval expansion.

A crumbling island fortress that seems to be covered in a field of stone crosses but is simply incomplete.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

A rocky Irish outcropping with a history of wealth, conflict, and ruin.