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

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

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

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

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.

One of the last few places in Manhattan that employed a pneumatic systemic keeps it on display.

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

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

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

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Try not to get slimed in Tribeca.

A line of blue paint marks the route of the inaugural parade.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

Decades before the scandal, this staircase on the river was a literal "water gate."

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

Where the U.S. government kept its actual treasure, before Fort Knox.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The walls of the iconic dome are hollow and have a secret stairway.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.