Chyello,
some food for thought, guys.
Jack, your mushroom/pod/garden proposal reminded me of a beautiful outdoor canopy designed for a restaurant in Spain - circular discs of Corten steel with geometric patterning - could be of some use?
http://www.dezeen.com/2011/07/28/castell-d%E2%80%99emporda-by-concrete/
Maddie - check out Herzog and deMeuron's 'Funf Hofe' in Munich, or, for that matter, any building that incorporates hanging gardens. I think Junya Ishigami did one too... maybe a hanging garden installation in the cathedral itself? Just putting it out there....
:) B2