If your family hails from London (or you just like cartography), you'll love this site: the British Library's virtual exhibition of historical maps of the city.

The 40 historic plats are organized on a Google map, making it easy to determine what areas they represent. The maps and images are also divided by time period, and you can access a zoomable version to see them up close. I especially like the map from 1653 with the lengthy title "A guide for Cuntrey men In the famous Cittey of LONDON by the helpe of wich plot they shall be able to know how farr it is to any Street."

For more resources for researching your English roots, you can always refer to our Ethnic Toolkit. The University of Texas also has a large collection of historic British maps in its Perry-Castañeda Map Collection.