A trading post in the North Pole where children send letters.

This whimsical stacked cabin looks like something out of a children's book.

The king of U.S. high points towers over every other peak on the continent.

Clean, cold drinking water flows from a nondescript pipe in a roadside rock face.

A high school astronomy enthusiast designed this model of our solar system to be traversed on foot.

During the summer, surfers in Alaska take advantage of this inlet’s unusual water patterns.

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

Please don’t anchor your boat onto the Department of Defense’s underwater data cables.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

Washington's iconic carousel has a nice piece of Civil Rights history.

Look closely and you’ll notice that the color changes a third of the way up the tower.

There’s a hidden military meme engraved on the World War II Memorial.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

The narrowest house in America is seven feet of pure spite.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.