"Search by location" finds all the photographs on our website that are associated with the location you select. As an example, the thumbnails that you see when you click on "Amersham" include all the photos that appear in our main "Amersham" location set but also include pictures that appear elsewhere. In this case they have come from "Special Collections", "Amersham, Lollard Martyrs" and "Amersham Museum".