As seen on www.dezeen.com in the post dated June 29th, 2009: Qui est "in", Qui est "out" by Yes We Can Architects. These London based architects used hula hoops in this construction. I love this!
The instillation was in the courtyard of the 18th century Hotel d'Aures music school as part of the Festival des Architecture Vives: In (side) Out in Montpelier, France last summer. 300 hula hoops were used on a tight budget of 900 Euros assembled by a team of 4 in 2 days. The title is after a song by Serge Gainsbourg, 1966.