The hill that gave the Massachusett tribe, and later the state, its name.

Mysterious stone tower featured in many alternative histories of the New World.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

This 3,500 pound obelisk was constructed with more than 1,000 reclaimed guns.

Ironically this massive termite is the mascot for a company that is acclaimed for killing his kind.

Unicorns, elephants, and bears, oh my!

This 50-foot rock formation looked like a face that was once believed to be that of a Native American chief.

A former major munitions plant that has been converted into a sprawling art space.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

At 207 feet, one of the world's longest continuous escalators.

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

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

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

A nostalgic bibliographic gem.

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

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

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

The most accurate timepiece in the world.

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

A much-maligned monument to teetotalism.