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

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

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

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

This tiny, hurricane-resistant house in Galveston is one of the city's most notable architectural oddities.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

A layered tribute to the work of mosaicist Isaiah Zagar.

This beloved marketplace mascot poops money and grants good luck.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

An eccentric priest's tribute to George Washington, this chapel tells the story of the American Revolution.

This stone tower marks a lookout point over the historic Washington Crossing, and maybe some buried treasure.

This might just be the TARDIS of bookstores.

An Irish Memorial commemorating those who perished due to potato blight.

Yo, Adrian!

This elaborate towering structure was once famed for its revolutionary height.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

World's first "penitentiary," meant to be humane, drove men insane.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.