The Église Saint-Sulpice was a major location in the story of the Da Vinci Code. Especially the gnomon was a major feature. It was stated that this gnomon was an indication of the zero meridian of Paris. Although it is very near the zero meridian, that is not correct. Gnomons were used in churches to define specific times in the year. They had as well a religious purpose (to define the date of Easter) as a practical purpose (when does spring starts whcih is useful to know for farmers when they have to start sowing their crops).