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

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

The district's only illusionarium supports free writing programs for local students with every purchase.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

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

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Decades before the scandal, this staircase on the river was a literal "water gate."

This lovely pocket park is one of the most under appreciated in D.C.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

Home to a vast and influential collection of Shakespeareana.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

There's a crumbling old mansion inside the Smithsonian National Zoo.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.