Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

Three hundred years of preserved Spanish colonial history in San Antonio.

This Manhattan skyscraper is a reminder of the brief but glorious age of urban air taxis.

A grand New York post office that is home to mailman Santas, scraps of postal history, and a pneumatic mail system.

A drawbridge named for a potentially intersex Polish national who fought alongside George Washington during the American Revolution, and an example of "Pulaski Red".

One-time largest man-made structure in the world will be a park in 30 years.

On the hills of Bay Ridge stands a house straight out of a fairy tale.

A remnant from the golden age of aviation still in use today, Pan Am's Clipper service took off from this Art Deco gem.

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

A decommissioned military complex that's now a modern industrial park.

A famous songsmith's custom piano, dubbed "High Society," is hidden just out of sight in one of New York's finest hotels.

Long-forgotten artifacts give incredible insight into New York's most glamorous hotel.

This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

This subterranean oyster house has been the pearl of Grand Central Station since 1913.

Visit the monolithic tomb of America's most famous general.

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.