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

A bit of retro transportation flair preserved in the world's largest department store.

Manhattan's lighthouse, erected at the insistence of the unsinkable Molly Brown.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

A popular European tradition makes its way to the states on one of America's most famous bridges.

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

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Ride the subways of yesteryear.

The "Seinfeld" diner.

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

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

One of only two commuter aerial tramways in the United States.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

A dilapidated dock tells the story of Titanic's missed arrival.

Try not to get slimed in Tribeca.

A crumbling hospital from the 1850s on Roosevelt Island.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

Illegal drag racing two stories beneath Chicago’s streets.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

A World War II-era submarine is stuck in the mud in New Jersey.

On the Hudson resides one of the largest clocks in the world.

These unassuming lighthouses have seen the first reading of the Pledge of Allegiance, the first wireless transmission, and more than one mystery.