The largest source of fossilized insects anywhere.

The romance of early commercial flight still fills this Art Deco destination.

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

Before Nixon, "watergate" meant canals.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

This taxidermy horse was a Civil War hero.

Perhaps the most scandalous statue of America's first president.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

An overlooked memorial honoring the local Washington residents who died in World War I.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

The "lovely red Vega" of the legendary record-settling pilot.

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

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

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.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.