I found this interesting link of a before and after map of Melbourne:
https://1945.melbourne/
Put it on a full screen desktop computer.
You can move the slider left or right to compare 1945 to now,
You can use the thumb wheel on your mouse to expand the size,
You can use the left click to hold the mouse to hold a position on the map and move it.
I can clearly see places I know well now, were farm land back in 1945.
I don't know if there's one for Sydney?
cheers
Allan