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

The 28,000-year-old specimen is remarkably intact.

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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

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

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

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

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

The school tested mustard gas for the U.S. Army during World War I.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The first memorial dedicated solely to the Black troops who fought for the Union.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

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

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

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

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

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

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

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

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

100 years later, they're still down there.

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