This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

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 derelict bit of transportation infrastructure hidden in the woods.

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

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

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

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

A wondrous old library overlooking the nation's capital.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A historic neighborhood church is reborn as a psychedelic arts collective.

This grand gothic brewery has been pumping out suds for over a hundred years.

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

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

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

The United States Capitol's former columns still stand.

Where the U.S. government kept its actual treasure, before Fort Knox.

A rotating cast of guys and dolls in front of a Washington, D.C. building.