A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

A line of blue paint marks the route of the inaugural parade.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

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

There’s a hidden military meme engraved on the World War II Memorial.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

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

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

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

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

This unique historical monument features large concrete spheres designed to resemble fallen stars.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

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

These unusual rooms on wheels are holdovers from the 1960s.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

Volcanic stone sentinels stand watch at a Korean Bell Garden in Virginia.

This stone gatehouse was once the entrance to a historic mountain resort, and it had a cameo in a cheesy cult horror movie.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’

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