Largest Roman Catholic church in North America.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

A nostalgic bibliographic gem.

A historic arena where the Beatles played their first concert in the U.S.

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

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

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

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

The site of the climactic scene from the classic horror film is now a historic landmark.

Look closely and you’ll notice that the color changes a third of the way up the tower.

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

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

This forgotten boat elevator was an engineering marvel in its heyday.

A portal into the bricked up canal that runs through the heart of Washington D.C.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Home to items never before seen by the public.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.