The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

The rogue roots are gradually consuming some of the historic marble grave markers.

The U.S. Fish Commission’s effort to mass produce carp.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

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

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

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

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

This beloved marketplace mascot poops money and grants good luck.

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

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

Experience a charming 1930s version of "infotainment."

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

A labor of love built by local hang-gliding enthusiasts, this ideal launch spot was outlawed by the authorities and has since been largely abandoned.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

Where the famed frontiersman was born, raised, and survived Quaker intrigue

Famously misunderstood wonder of the ancient world

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

In an odd geographic anomaly this city borders two different states on opposite sides of town.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

A massive Montreal stadium that has seen nothing but trouble since its inception.

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

Alexander Hamilton’s creation caused quite a bit of controversy.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.