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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

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

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

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

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Largest Roman Catholic church in North America.

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

The most accurate timepiece in the world.

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

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

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

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

She stares out across six lanes of traffic, clutching a musket and infant with determination.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

FDR's Art Deco hospital tower was hopelessly inefficient.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

This ruined quarry once produced the distinctive red sandstone used for construction projects in Washington, D.C.

Built in 1815, the stabilized ruins of the grist mill and sawmill are now gated, but interpretive displays on the features and functions of the mill preserve its history.

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

The whole world in one water tank.