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

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

The discovery site of the "Capitalsaurus," the official dinosaur of Washington, D.C.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

Art deco landmark on the outskirts of Washington, D.C.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

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

A historic ruin just 20 feet away from a busy highway onramp.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

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

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

The most accurate timepiece in the world.

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

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

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

An Industrial Revolution-era public work that purified water using nothing but sand.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

Largest Roman Catholic church in North America.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The national park was once a plantation estate.

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

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

A painfully obvious spy house sits right across the street from the Russian Embassy.