The oldest standing structure in downtown San Diego.

These two K-9 memorials commemorate the sister cities of Edinburgh and San Diego.

This historic Chinese church was relocated and revived as a museum that preserves and celebrates Chinese art, history, and culture.

The classic Atari game's iconic aliens have invaded downtown San Diego.

This futuristic bridge is one of the longest self-anchored pedestrian bridges in the world.

A sculpture of the famous photograph stands on San Diego's "Greatest Generation Walk."

For over 70 years, this house was home to a pioneering Black artist and educator.

The oldest surviving one-room schoolhouse in Montgomery County, Maryland.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

These abandoned waterworks are crumbling into the Potomac River.

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

Right next to departures—how convenient!

Long buried under the 20th-century landscape, this lift lock of the Alexandria Canal is the lone remnant of an ambitious early American transportation project.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

This pharmacist and his patient greet visitors to the National Community Pharmacists Association.

A gift from Japan, 17th-century lantern stands among the cherry trees at D.C.'s Tidal Basin.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

Taste the white whiskey that the United States' first president once distilled and enjoyed.

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

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

FDR's Art Deco hospital tower was hopelessly inefficient.

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

The former home of Thomson Francis Mason, the mayor of Alexandria from 1827-1830.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.