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

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

A building so large that it has its own weather.

Electrical pylon in the shape of Disney's beloved mouse.

The plants form a living library and laboratory for researchers and students at Michigan State University.

The world's longest known cave system.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

A real flying saucer, contracted by the U.S. Air Force.

Inside houses a vast collection of military aircraft and missiles spanning the ages.

Ride the subways of yesteryear.

This bronze sculpture was inspired by a photograph of Martin Luther King Jr. and his wife embracing after he won the Nobel Peace Prize.

A three-piece musical sculpture installed between the subway tracks at Kendall Station near MIT.

The phrase "the shot heard around the world" was coined after a skirmish at this bridge.

One of the last remaining movie theatres in the country that features a rear-projection system.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

A tiny plaque marks the location of the water source that facilitated the birth of modern-day Boston.

Dedicated to one of the darkest moments in Irish history.

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

One of the indelible moments of the American Revolution took place at this location.

Centuries-old hoofprints and wagon tracks reveal themselves after a good winter storm.

This small glass cube is a peaceful out-of-the-way sanctuary at the busy airport.