Once upon a time I saw a very old OS map of Exeter in the Treasures of the British Library exhibition. Now through the miracle of Google, I know that it was the Drawing for the first edition Ordnance Survey map of Exeter. 1801 Maps OSD 40.(3)
But even more miraculously, the BL has a georeferencing project, to place OS drawings “that portray the lanscape [sic] of England and Wales before the onslaught of industrialisation made its mark” over the current landscape.
Exeter 1801 was one of the pilot maps, and it is available overlaying Google Earth, with the ability to zoom in and out and change the transparency. For example, I can easily compare the old quarry with the roads and houses that are off Quarry Lane. REALLY cool, and very excited!
And there’s another great site showing what maps are available on Visions of Britain, though without the overlay facility. Search on Exeter.