Beneath Kingsford Country Park, north of Kidderminster in Worcestershire, England, the Drakelow Tunnels are a former underground military complex. Make that a “top secret” underground military complex.

Not far from Birmingham, the tunnels have a colorful history. They were dug between 1941 and 1942 in order to build a “shadow factory” for the Rover car company, mostly machining parts for aircraft engines. A shadow factory was a method of production devised in Britain in the late 1930s, whereby both knowledge and machinery could be cross-pollenated between industries, by experts “shadowing” each other, as at Drakelow between auto and aircraft manufacturers.

The underground works were comprised of three and a half miles of tunnels, and were used throughout World War II and for most of the 1950s, first for aircraft then for tank engines. By 1961 a different kind of shadow fell over Drakelow. The British Government took half of the tunnels and converted them into a top secret “shadow government” headquarters, one of thirteen such sites in the UK forming a network of underground bunkers like Drakelow. This was the height of the Cold War era, and the thinking was if things up top got out of hand the British Government could still run the country from down below.

Drakelow soldiered on in secrecy until 1993 when it was decommissioned, and the miles of tunnels and outdated equipment was sold into private hands. Since the sale, the Drakelow Tunnels Preservation Trust has been working to restore the complex to its former glory, hoping to create a comprehensive Cold War Museum. They have their work cut out for them, but there are sections that are already open for visitors. There’s a lot to discover in the shadows down there, but maybe soon, not so many secrets.