This project was located near March in Cambridgeshire, UK. The Prime Meridian, which is used to define all the world's time zones, runs from Greenwich in London up through the east coast. The camera and mirror were positioned on this meridian, with the mirror aligned with the camera to reflect sunlight into the lens when the sun passed overhead at midday. At this moment, when the sun is exactly above the Prime Meridian, it is 12:00 noon in Greenwich.