Got a really fascinating book out of the library - its by a guy called Steward Brand and its called "How Buildings Learn" subtitle What happens after they're built
ISBN No 0 75380 0500
Its full of pictures of buildings changing over the ages and discussions of what makes a successful building for the long term ( i.e. one that people can adapt as their needs change ).
Jackie
PS if you are an architect you may need to go for a calm down walk round the block after reading some of the chapters.