I wish I had seen these moss walls by Norwegian design studio PUSHAK while I was in London last week! From Inhabitat:

Dubbed Moss Your City, the project was installed during the London Festival of Architecture as a part of the foundation’s international exchange program, which promotes emerging architects in both Norway and the UK. The project encourages individuals “to become foresters in their own city” by participating in guerilla gardening actions.

[Thanks, Andrew!]

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Moss Graffiti