Urban Growth Explorer

Another of the outcomes from the ESRI UK Annual Conference was awareness of the Urban Growth Explorer tool
This was developed in association with the National Library of Scotland, who have previously released a huge tranche of historic maps, which have been released and made available through various interactive tools.
This uses a swipe tool to explore the changes in the growth of key cities. Another similar tool here.

It's also worth remembering that there are some similar tools in Digimap for Schools - here's a short video explaining how that can work too...