When it opened during the final years of the embargo, all the drinks and cigars were free.

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.

Largest Roman Catholic church in North America.

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

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

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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.

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 historic neighborhood church is reborn as a psychedelic arts collective.

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

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

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

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

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

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

Crammed into several rooms of a Staten Island home, this museum is a vodka-soaked paean to the pleasures of drinking.

The home of possibly the least-loved U.S. president stands as a sort of unpopular Monticello.

A reservoir of vintage pinball machines and arcade games for the nostalgic and thrill seeking.

Mysterious rocks that ring musically when struck.