C. Th. Sørensen, a Danish landscape architect, noticed that children preferred to play everywhere but in the playgrounds that he built. In 1931, he imagined "A junk playground in which children could create and shape, dream and imagine a reality...His initial ideas started the adventure playground movement.
The first adventure playground opened in Emdrup, Denmark in 1943, during World War II. In 1946, Lady Allen of Hurtwood visited Emdrup from England and was impressed with "junk playgrounds." She brought the idea to London. These "junk playgrounds" became known as "adventure playgrounds."