Historic psychiatric asylum and most-filmed location in the Great White North.

This charmingly homemade amusement park has been growing for 40 years.

An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

An abandoned 19th-century hospital now swirling in ghost stories.

This 1920s Dutch barge is now a floating bookstore.

Its collection includes a broad array of social, geographic, graphic design, and political history.

A mysterious shape catches the eye in this 16th-century painting.

The commemorative stone column conceals a secret laboratory.

This unique bridge curls up like a caterpillar to let boats pass and then unfurls again to span a small canal.

The fences outside some of South London's estates are made from recycled World War II stretchers.

Where condemned pirates met their grisly end at the gallows on the River Thames.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

The London statue that imitates passersby.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Lovers proclaim their unbreakable bond by leaving their names on locks fastened onto the Shoreditch fence in East London.

Bronze sculpture celebrating the relationship between Churchill and Roosevelt.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

A promising candidate for the lost rock laid by George Washington was unearthed, but the hunt is still on.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.