This nine-story building is the oldest standing skyscraper in D.C.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

When it comes to handsignals (and colonialism) rock always beats scissors.

This unassuming passageway played a key role in one of the most important events in U.S. history.

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

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

Go take a picture with the inventor of the daguerreotype photographic process.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

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

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

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

A clone of a cloned tree that was so important it allegedly had its own guards.

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

Seemingly unremarkable items like empty sushi trays, chef hats, and freshness stickers are being preserved so future generations can look back on this beloved cultural import.

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

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

Obscure Freemasons still live in D.C.’s largest private residence.

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

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

There's a crumbling old mansion inside the Smithsonian National Zoo.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

The most decorated dog of World War I is preserved in the Smithsonian.