The secret wartime bunker built on the platforms of an abandoned Tube station.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

The last remaining example of the boatmen's perches that once dotted the south bank of the Thames.

The broken skateboards that became a poignant memorial to a murdered skater.

This pump on the bad side of Victorian London betrayed a horrifying revelation about the water supply.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

The wooden telephone box hidden away in London's Piccadilly was the original prototype of the iconic kiosk.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

This small collection of rare books was uniquely locked up for safe keeping.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

Once a train station along the Great Eastern Railway this vibrant coffee shop and bar is where members of London’s creative class mingle.

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

The remains of Crystal Palace Great Exhibition of 1851.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

Hidden beneath the streets of London is a secret subway that only carried mail.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Giant pinnacles in the sun-scorched lands of Southern Utah have been nicknamed "white ghosts."

Rippling sand dunes frozen in the Arizona rock.