When the issue is the relation between child and architecture, playground is always a strong example. Indeed since 1947, when the dutch architect Aldo van Eyck (1918-1999) start the famous Amsterdam experiences, playgrounds were designed all around the world with several different material, shapes and results.
One of the best sites I found is this swiss site called Architekture Fur Kinder where is possible to find several references and links with other material.
http://www.architekturfuerkinder.ch/