If you haven't already, then you should take a look at the London Sound Survey

I've posted about this before, but it really is worth revisiting as it changes regularly and is added to of course, so if you haven't heard of or visited the London Sound Survey then this is something you really should do, and even if you have, but haven't been to the site for a while you should take another look, especially if you have an interest in field recording or found sounds.