The National Library of Scotland is actively adding Ordnance Survey town plans for England and Wales online dating from the 1840s to 1890s. Presently with over 400 town coverage, these are high resolution 1:500 scale — one inch on the map represents 42 feet. You can select a town or use a zoomable map to home in on the exact area of interest.
NLS is extending coverage in November and December 2021 and stitching them together overlayed on a Google map so you don’t struggle with the Iron Law of Maps – the area of interest is always at the intersection of two or more maps.
Naturally, NLS has a wide assortment of maps for Scotland. Access the complete collection from https://maps.nls.uk/os/