Following up on a previous post, the National Library of Scotland now has online old maps and town plans for more than 380 English and Welsh towns (all those with more than 4,000 people) at the highly detailed scale of 1:500.
NLS is georeferencing these maps so they can be easily compared to the present day, or to other historical dates (for example Leeds in 1840s compared to the 1880s).
Browse a list of all the towns with links to view maps
Browse a clickable map of England and Wales
OS Town Plans of England and Wales home page