Alan Dein discovers the surprising history of the adventure playground. The very first adventure playground opened in Emdrup, Denmark in 1943. As resistance grew against the Nazi occupation, two men pioneered a unique space, the children's world turned upside down. They were forged in the ideas of modernist and radical architects and exported to a postwar Britain by the campaigning Lady Allen of Hurtwood. The rubble and rubbish of the nation's shattered cities were now reimagined as spaces for all sorts of adventures.