This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

These five Art Deco homes were meant to solve the "small house problem."

This suburban house is made of dirt, and almost sparked a revolution in home construction.

The former home of Dr. E.B. Henderson, also known as the "Father of Black Basketball."

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

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

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

Once the largest trading firm of enslaved people in the U.S., this building is now a museum that preserves Alexandria's dark past.

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

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

An original apothecary from 1792.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

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

A superbly preserved example of Georgian residential architecture that was once home to one of the founders of Alexandria, Virginia.

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

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.

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 narrowest house in America is seven feet of pure spite.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

This "castle" is actually a limestone and quartz formation hidden along a trail.

Built to defend Washington D.C. during the Civil War, this fort became a post-war nucleus for a thriving Black community.

This cannon dating to 1755 has stood guard at this suburban intersection since 1915.

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.