A collection of maps dated from 1630 to 1930 have been uploaded online for you to browse through. The maps are cleverly overlaid on to a Google Maps map and allow you to see what various areas looked like a long time ago.
Some of the old maps go in to street level detail where as others cover large regions such as western america from 1845.
The maps are available on David Rumseys historical map collection site which can be viewed over here. Also note the transparency options found top right that allow you to fade in and out the newer maps so you can compare the modern day mapping to the old mapping.