Every drop of D.C. tap water flows through this old waterworks.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

The span is crooked and made from two older recycled bridges.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Daily lunch spot for many of Washington, D.C.'s cab drivers.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

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

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A historic neighborhood church is reborn as a psychedelic arts collective.

This grand gothic brewery has been pumping out suds for over a hundred years.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

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

The original vault that held the president's remains still stands, empty, not far from where he was finally buried.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

For 32 years the famous Ringling Bros circus troupe spent winters in this sunny spot in Florida.

This grisly headstone doesn’t seem to be resting in peace.

The narrowest house in America is seven feet of pure spite.

Affectionately known as "Lord Bot," this historic statue has a cult social media following and rightly claims to be “the most metal inhabitant of the Wren Yard.”

A collection of over 2000 air-moving devices of all kinds displayed in the Fanimation headquarters.