Recognize this building? Google now have 3D mapping of inner city London in Google Earth and on Google Maps (when you zoom right in.) To access the view in Google Maps, click the “Earth” button on the bottom left, then click the tilt button below the compass on the right, to access the 3D view. via a Mapping London blog post.
You'll need to use your imagination if you want to see how the city looked when your ancestors lived there. Get inspiration from this video.