The oldest brick house in the state of Ohio.

Hidden on two floors of downtown building, the library has an incredible deal on rent.

One of the few beardless depictions of Lincoln, George Grey Barnard's 1917 was denounced by many—including Lincoln's own son.

Overlooking the Colorado Convention Center is this giant sculpture made from thousands of triangles.

This quirky museum has a collection of more than 15,000 bobblehead dolls.

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Though his role as the inventor of baseball may be up for debate, fans still festoon Doubleday's grave with baseballs.

Recorded as the first person buried in Arlington Cemetery.

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

A much-maligned monument to teetotalism.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

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

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

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

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

An overlooked memorial honoring the local Washington residents who died in World War I.

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.