On this map are a number of pins. Click on a pin to go to either an article or an item in the archive that references that location. If there are a lot of pegs in an area they form a cluster and a number appears in a circle to indicate the number of items at that location. Use your mouse scroll wheel or the controls in the top left-hand corner to zoom in and unpack the cluster.
Click on the symbol in the top right-hand corner of the map to display an overlay of an historical map. Use the slider to move between the maps.