Good idea: Maps are on the SLOW routegadget.
http://www.slow.routegadget.co.uk/rg2
I think most of it is public access, although London is always being redeveloped.
After 1000 years you might have thought they'd got it right by now :)
Most fun from an O-point of view is the Barbican (e.g 2014), and from a touristic viewpoint, courses which head down past St Pauls to the river (e.g. 2010).