A haunting tribute to pioneering photographer Clover Adams.

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

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

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.

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

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

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

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

"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!”

The national park was once a plantation estate.

The oldest continuously operating fish market in the United States.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

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