The site of William McKinley's tragic assassination is only marked by an underwhelming boulder.

Jimi Hendrix's legendary recording studio in Greenwich Village.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

Cryptic messages embedded in the New York City sidewalk.

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

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

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

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

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

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Though his role as the inventor of baseball may be up for debate, fans still festoon Doubleday's grave with baseballs.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

This haunting monument honors the victims of 9/11.

Nassau Hall has served as army barracks, a museum, and played a key role in the American Revolution.

The final resting place of many of New Jersey's most famous residents, including U.S. history's most in-vogue antagonist, Aaron Burr.

This Las Vegas casino boasts one of only three spiral escalators in the United States—an engineering wonder.

These markers are used to determine the ground stability of the Strip.

This Nevada lake holds its titular natural pyramid and, if the legends are true, a number of dangerous spirits.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.

Detroit’s downtown castle is one of the oldest structures in the city.