Some months ago, Russell Miller noticed that London was filled with metal posts that are left embedded in the ground long after the signs they once supported are taken away. So he began to photograph them for his website, taking particular interested in the way people walk past these rusting remnants without even noticing. And then he told me about it.
I think they are great. Here are a few examples, but for more check out Russell’s website – We Do This Because We Forget.
The Great Wen 
Cyclists know where they are and what they’re for…
They are all yarn-bombing targets 🙂 http://hackneycitizen.co.uk/2012/02/23/hackney-gets-yarn-bombed-mare-street-trees-get-woolly-makeover/
Excellent. While we’re on sites specialising in pictures of odd quirks in the street, I really like this one…
http://misplacedmanholecovers.co.uk/
I’m sure they are put to very good use by cyclists and dogs for very different purposes, we hope! There must be hundreds of them around the country, they should be removed and put into storage until a use is found for them. Perhaps they are waiting to be claimed and recycled? Whatever the purpose, I don’t know if we could call it, in any way whatsoever, architecture.