Historic Maps of London
layersoflondon.org
layersoflondon.org
and a fun way to navigate some of them: https://maap.columbia.edu/place/then.html That was a project I worked on in ~2006 when Google Maps was more 'new'. At the time I was very proud because Google Maps still had a 'jumpy' zoom interface and I wanted it to feel immersive to 'enter' the maps by 'falling' into them.
Later that year, Google Maps added the same feature, which I don't attribute at all to this project, but it was cool to do it before them.
[1] https://maps.hungaricana.hu/en/map/?layers=google-hybrid%2Cv...