In Edwin Hubble's hometown, a scale model of the groundbreaking telescope that was named in his honor.

A phone booth that combines public art and climate change awareness.

This is one of the very few intact windmills built by the Knights of St. John in the island nation of Malta.

A Jenga-style cylindrical tower of books that appears to go on forever.

Only open for two days a year, this church links ancient Greek and modern Christian celebrations.

This lesser-visited World Heritage site in Athens boasts an impressive ensemble of medieval gold mosaics.

The bones of prehistoric animals and early signs of human habitation have been found inside Malta's "cave of darkness."

People have been making salt here using traditional methods for centuries.

The model behind the iconic 3D test model.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

This Ottoman-era church is hidden amid a busy tourist area.

This church is dedicated to the patron saint of seafarers.

Τhis feline monument commemorates fallen soldiers on a field that saw many, many battles.

This 18th-century former mosque held the first Hellenic Parliament.

A closer look at this somewhat faded hotel by the Corinth Canal reveals the architectural undertones of a genius.

A staircase made of gravestones leads up to this church built into a giant rock.

This slumbering beast honors the Bavarian soldiers who died in Greece during a 19th-century typhoid outbreak.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

The ruined doorway is a portal to the building's turbulent and torturous past.

This historic structure has been used as a mosque, a barracks, a prison, a school, and a bakery.

The site where hundreds of Greeks were tortured by the Nazi secret police is now a cosmetics store.

Step inside an ancient beehive tomb built for a mysterious cult hero.