Overlaid Maps
Look at
this map of Leith. Now move the
blue dot slider 
to the left and the map
fades
between an old map and the new satellite image. Also, look at
the left side and you will find a selectors named "Select a Category"
(usually Scotland or Scotland Town Plans would be your best bet) and
then "Select a Map / Map Series" which allows you to change the overlaid map. The six-inch series
or, if available, twelve-inch series are the best for detail. The Roy maps are wildly inaccurate but
have a quaint historical perspective to them.
Once you have arrived on the map you can pan and zoom as normal.