On Friday 6 September, architecture students and recent graduates from around the world came to visit the Coeur vert as part of the Ateliers de Cergy workshop. These workshops on urban planning and development, held every September, set out to study the development of particularly important or problematic sites in France. This year’s theme is the future of the Pierrelaye plain in the heart of Greater Paris. The Coeur vert has a similar background to the Pierrelaye plain: soil polluted by 100 years of waste water spreading, until a government order brought the local market gardening industry to a sudden halt in 1999. So students were able to see first-hand why CA2RS chose to develop the plain into a multi-purpose park: an agricultural business park producing biomass for eco-construction, as well as an eco-friendly landscaped park.