My favourite mapping site is at: Mapping Layers of London
I am extremely grateful to David Hale for allowing me to link to his maps at the MAPCO site , a fantastic resource.
Here is the Scottish nls site (national library of Scotland) - There are over 86,000 maps as high-resolution, colour, zoomable images. The maps date between 1560 and 1961 and relate primarily to Scotland, but also maps of England and Great Britain, Ireland, and Belgium.
I love this site which allows a comparison between the mappings of 1746, 1869 and today - brilliant. At locatinglondon,org
There are a considerable number of maps on the mapco site which are absolutely brilliant, e.g. in 1857
The assorted Maps of Tower hamlet is an absolutely brilliant resource I have been keeping to myself - it allows simultaneous views of different peiods in time - i.e. 1745, 1766, 1801, 1802, 1822, 1831, 1844, 1853, 1882, 1952 & 2000 for bethnal Green & Stepney.
And more Maps of Tower Hamlet in 1745, 1801, 1831, 1853, 1861, 1875, 1882, 1952 & 2000 for Bow, Bromley & Poplar.