The National Library of Scotland provides some very impressive mapping resources. The side-by-side maps allow you to view any area of the UK with a modern map on one side and a second map providing an alternative view of the same area.
In the above example, we use a modern satellite view on the right and an old ordinance survey map on the left. Each map has a layers selector option where you can choose what map type you wish to display. You can also choose to display LIDAR maps.