Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

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

A haunting tribute to pioneering photographer Clover Adams.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

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

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

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.

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

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

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

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

There’s a special club house at the top for the bell ringers.

A battleship’s mast sits atop a turret-like memorial, commemorating those who lost their lives in one of the precipitating events of the Spanish-American War.

A nostalgic bibliographic gem.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

Home to a vast and influential collection of Shakespeareana.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

At 207 feet, one of the world's longest continuous escalators.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."