A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

These small stands sell Malian snacks to worshippers and passersby after Friday prayers in Harlem.

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

This 15th-century mosque is a beautiful blend of Hindu and Islamic architecture.

This 16th-century mosque is the hallmark of the African architectural legacy in India.

These haunting ruins of a 700-year-old Prehispanic city have witnessed centuries of wars and massacres.

The last remaining colonial-era Italian church in Old Goa.

This colonial fort is an intriguing example of Renaissance military architecture.

This Bronx apartment building is officially recognized as the birthplace of hip-hop.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A large boulder marks the place where the island of Manhattan was purportedly "sold" to the Dutch.

This Dutch Colonial home is the oldest remaining farmhouse in Manhattan.

Seriously good slices of Sicilian pizza lurk at the back of the Bronx's oldest enclosed market.

Hidden inside one of the world's most well-visited zoos is a secret plaque promising eternal life.

Manhattan and the Bronx have been playing tug-of-war over this former island neighborhood for more than a century.

The end of the 4 Line is also the end of the line for 300,000 souls in one of NYC's most illustrious cemeteries.

This old estate is a remnant of when the Bronx was a popular summer destination for wealthy New Yorkers.

Final resting place of Typhoid Mary.

The largest game reserve in Africa is home to thousands of species but refuses to house humans.

Stay in your own little bubble.

Tucked in the back of this amazing antique store is an important piece of medical history.

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

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."