During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

Conveniently located within binocular range of a nuclear bunker, the "summer camp" area was a painfully obvious spy house.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

Taste the white whiskey that the United States' first president once distilled and enjoyed.

Thomas Jefferson's estate is home to hundreds of varieties of historic fruits and vegetables.

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

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

The U.S. Army's giant warehouse of war art includes Hitler’s watercolors and Norman Rockwell oil paintings.

The FBI's urban training course may have the highest fake crime rate in the world.

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

This museum sits on the site of a decommissioned military communications base.

An eccentric company offers eccentric millionaires the opportunity to have spaceflight-related experiences.

The only place for a truly presidential dram.

A bunker "with enough U.S. currency to replenish the cash supply east of the Mississippi" in the event of nuclear war now protects nitrate film.

This sprawling museum holds one man's giant collection of real tanks.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

This airfield is home to a number of retired vintage planes in various states of disrepair.

The first statue of Christ sleeping on a bench in the United States confused its affluent parish.

The U.S. Supreme Court's secret Cold War relocation facility in the mountains of North Carolina.