This little place is a gem, and its immediate environs the most pleasant spot we've found in Montpellier. According to the Routard, it was cleared to make way for a new church in the early 17th century. When that project was abandoned, the grounds became public.
Update (2009-08-01): I don't know my way around OSM very well, and just now stumbled onto another representation of Place de la Canourgue at http://api.openstreetmap.org/browse/way/8105279. This one has links to its nodes and connected ways. Are these "browse" URLs as cool as they look like they could be?