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

A relic of FDR's brief foray into utopian urban planning.

Perhaps the most scandalous statue of America's first president.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

An overlooked memorial honoring the local Washington residents who died in World War I.

There’s a hidden military meme engraved on the World War II Memorial.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Horrifically creative torture devices and shame punishments line the walls of this chilling museum.

The oldest continuously operating fish market in the United States.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

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

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

The U.S. Fish Commission’s effort to mass produce carp.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

The most accurate timepiece in the world.

D.C. once had its own tiny rival to the New York Stock Exchange.

The rooster who crossed the road lives on forever in Takoma Park, Maryland.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

The tunnel under the Capitol Building where Congress takes out its trash.

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

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

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