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

There’s a special club house at the top for the bell ringers.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

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

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

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

The site of the climactic scene from the classic horror film is now a historic landmark.

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

Parking garage where Bob Woodward met Watergate source "Deep Throat."

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

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

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

A much-maligned monument to teetotalism.

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

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

A spectacular tribute to statesman and philanthropist Andrew Mellon.

A secret greenspace hides atop a Capitol parking garage.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

The walls of the iconic dome are hollow and have a secret stairway.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

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

Look closely and you’ll notice that the color changes a third of the way up the tower.