A giant time capsule not scheduled to be cored until 2040.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

A very classy 1920s-era bar right in Grand Central Station.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

One of the few remaining American elm trees in New York’s Tompkins Square Park was the birthplace of a new religion.

A reminder to choose water over wine since 1888.

Salute the leader of the proletariat.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

America's first federal monument.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

Once home to an aristocratic family and a workers' organization, this intricately tiled building now houses a chain restaurant.

This one-window stand has been home to a giant vat of slowly simmering meats and an array of unique tacos for almost 50 years.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

The oldest continuously operating fish market in the United States.

Home to items never before seen by the public.

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

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

This botanical garden boasts sculptures, industrial ruins, and an endorsement from the Dalai Lama.

Dating back to the second century, vestiges of prehispanic mural paintings are found in this underground palace.

The now-public home of a renowned art collector is full of unique pieces from viceregal and 19th-century Mexico.