The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

The Columbia Road Flower Market is now open every Sunday, rain or shine.

A high-end clothing boutique with a curious basement art installation.

Charles Babbage's proto-computer, painstakingly brought to life.

Pop culture has helped to keep this iconic British building from being destroyed.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

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

Traveling collection of amazing automata.

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

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

Only spot in the world where an HVDC powerline, a single phase AC and a three phase AC powerline all meet.

Only electricity pylons carrying both AC and DC circuits.

This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

Walk 2,300 feet above the ground on the "Troll's Tongue."

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

Digger attempting to hide itself under 300 tons of rubble.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.