This is truly remarkable. Launched last week, Collage, The London Picture Map allows you to trace London’s visual history street by street. Supported by the City of London Corporation, it’s the result of two full years of digitizing and mapping images from the London Metropolitan Archive and the Guildhall Art Gallery, which together possess the largest collection of London images in the world.
Check out the interactive map here. I'm going to have hours of fun with this.