This overlooked street light once served as a KGB dead letter box.

Claiming to be the oldest hat store in the world, this historic haberdashery had a hand (and a head) in the creation of the Bowler.

Revel in the Victorian splendor of the world's oldest eating establishment inside a museum.

A relic of Victorian grandeur hides beneath a busy South London road.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

This London plaque marks the spot where David Bowie's famous alien made his debut.

Hidden behind a wall for decades, this masonic lodge was only rediscovered during renovations.

A collection dedicated to the treatment of disease, held in London's oldest hospital.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

The National Park Service’s best-kept secret with views that rival any in D.C.

Garments from across the globe call this hidden gem home.

This groundbreaking 16th-century map is known as "America's birth certificate."

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

There's a crumbling old mansion inside the Smithsonian National Zoo.

The national park was once a plantation estate.

There’s a hidden military meme engraved on the World War II Memorial.

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

A wondrous old library overlooking the nation's capital.

The beautiful, fruit-covered facade hints at this building's former life.

Taxidermied cartoon heads, unseen illustrations, and famous characters all reside in this small gallery space.

This Birdsill Holly fire hydrant is the remnant of a very different type of hydration innovation.