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.

A wondrous old library overlooking the nation's capital.

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

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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

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.

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

The United States Capitol's former columns still stand.

There is no trying to fall in love with this Star Wars fountain, you just do or do not.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Furniture tries to escape an abandoned building in San Francisco.

Its buzzing collection honors vibrator history.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

Half of a house.

The remains of a 12th-century chapter house in Golden Gate Park.

The taxidermied remains of the "last wild grizzly bear in California" and of the symbol of the state of California.

The legendary statue-hating superintendent of Golden Gate Park is honored with... a statue.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.