Paris Museum Quai Branly got their green wall two years ago--a 4 story vertical garden on an exterior wall of the building. Now Madrid's newly opened CaixaForum museum has one too. It is 24 metres high and takes up one wall of the square in front of the building. It has 15,000 plants of 250 different species and has become an instant drawing card to the area. It forms a striking contrast to the restored building which has a two-storey addition of rusted iron on top of the original. The architects, Herzog & de Meuron, said that they wanted to "create a very unusual encounter between the rough and the natural, ...to incorporate nature so there can be the smell of a garden where you would not expect it."
The creator of the garden is Patrick Blanc, who has made quite a speciality out of them all over France and coming soon to China and the UK. He believes that they could be created everywhere--in parking lots, train stations, the metro, "those difficult spaces where you don't expect to see greenery". Interestingly, growing plants out of a wall is not as heavy as it seems. Having researched the world's jungles and rainforests as his basis, the weight is less than 30kg per square metre and can be installed on any wall. :: Financial Times and :: The Art Newspaper