This abstract sculpture is rumored to cast a hammer-and-sickle shadow once a year.

To find the "unicorns of the deep" you've got to go downstairs.

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.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

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

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

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

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

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

A computer bug so primitive it was an actual insect.

Home to a vast and influential collection of Shakespeareana.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

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

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

The national park was once a plantation estate.

It was once the base for a series of domestic terror attacks.

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

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.