The Guardian of Tallinn.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

A subterranean house of worship carved right out of the bedrock.

Flamboyant architecture from the turn of 20th century.

A black cat protests the City Guild in Riga's Old Town.

An abstract monument to a symphonic composer.

Rodin's famous depiction of Dante's 'Inferno', amidst a sculpture garden of many of his other works.

A vast city of the dead, where the deceased outnumber the living by more than a million.

A 1920s speakeasy that had rum runners racing up and down the shores of California.

A classically inspired temple in Redwood City.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

An extensive collection of ancient Egyptian artifacts and mummies.

The headquarters of a secretive order is also a beautifully-designed park.

A house built from trash known as the poor man's Hearst Castle.

Thousands of turbines whir at the origin of North American wind power.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

Space-age minarets towering over Islamabad.

A 17th-century mosque that was used for war more than worship.

Lonely minaret stump of a destroyed city.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Three columns of volcanic rock shoot out of the ocean.

Iceland's largest lagoon is home to stunning multi-colored icebergs.