A 10-foot-tall concrete Alley Oop statue left over from World War II now stands on the side of the road.

A museum dedicated exclusively to aircraft used in the military.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

The real-life site of Ichabod Crane's infamous gourd attack.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

A building shaped like the Army Corps of Engineers logo, because why not?

A historic ruin just 20 feet away from a busy highway onramp.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

An Industrial Revolution-era public work that purified water using nothing but sand.

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

A derelict bit of transportation infrastructure hidden in the woods.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

A painfully obvious spy house sits right across the street from the Russian Embassy.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

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

This grand gothic brewery has been pumping out suds for over a hundred years.

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

Home to items never before seen by the public.

The United States Capitol's former columns still stand.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

America's first public mental health facility.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.