Started as a kitchen garden, now the second largest botanical garden in the world.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

This TV tower once secretly housed a GDR intelligence team.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

Fall down the rabbit hole into a surreal journey of human consciousness "from ass to soul."

Art and a pun, all in one.

A surreal museum of extraordinary industrial objects.

Super-heavy Nazi architectural experiment.

A student driver's nightmare.

Shakespeare, David Bowie, Dr. Who, the Saxons, Druids and Romans are all claimed to have all made their mark on these massive man made tunnels.

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

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

Remnants of a Victorian garden feature sitting in public woodland.

A Victorian park cemetery, standing on the site of what was once the Great North Wood.

The remains of Crystal Palace Great Exhibition of 1851.

The curios of pharmacist and collector Henry Wellcome.

An unusual round church in London with a Templar past.

London's smallest police station is barely the size of a phone booth.

The largest of London's subterranean rivers and once a mad, bad center of London life.

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

The anatomical-pathological collection of a man who changed surgery.

An intriguing three-sided folly is a testament to one man's devotion to Catholicism and the number three.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

A historic arboretum and non-conformist, non-denominational park cemetery.