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

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

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

Decades before the scandal, this staircase on the river was a literal "water gate."

This historic boathouse was constructed using salvaged lumber from burned barns.

A massive, majestic mammal watches over pedestrians from his perch atop a former B.P.O.E. lodge.

The only surviving 19th-century water-powered mill found in the Washington, D.C. area.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

Built in the 1850s, this church was of the first five churches constructed in Harper's Ferry.

The "mysteries" of this quintessential roadside oddity were almost destroyed by neglect but were saved by fans of kitschy wonder.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

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

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

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

A former major munitions plant that has been converted into a sprawling art space.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

The former home of the man whose radical ideas changed the nation.

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.

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

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

Remnants of a storybook amusement park hidden behind a strip mall.

The romance of early commercial flight still fills this Art Deco destination.

The "lovely red Vega" of the legendary record-settling pilot.