Prompted by @shaungdavey and his post about the excellent #NationalLibraryOfScotland 's online #maps here is my favourite version

https://maps.nls.uk/geo/explore/side-by-side/#zoom=5.0&lat=56.00000&lon=-4.00000&layers=1&right=ESRIWorld

Side by side historic and current maps up to 60" scale (yes 1:1056) maps of some Victorian city regions