These maps go back to the early 19th century.
It is free to use, with digitised aerial photographs and historical maps of Norfolk. There are:-
Once you have specified a starting location (by grid reference, place name or postcode), the interface allows panning and zooming, plus of course choice of map to display. The controls aren't up to the high standard of modern web-based maps, but the service is fast and the maps are pretty seamlessly stitched together. You do have a choice of large images, but that generates a super-wide but regular height image, which doesn't help much more with getting a perspective of the area you're viewing.