Ordnance Survey grid references and Global Positioning Satellite coordinates are two complementary ways to locate oneself in urban and rural environments. I am using both systems to chart a section of the Ridgeway that I regard as home ground, the route from Liddington Castle, an ancient hill fort, to the more easterly Charlbury Hill. The trigonometric points at both locations act as boundaries between which I have identified points of interest such as objects and structures, both temporary and more enduring, that characterize the area. Through attributing waypoints (electronic pinpoints) to these features, I am constructing a personal map of the space.