Saint Sulpice Roman Catholic Church, it is only slightly smaller than Notre-Dame, at 113 metres long, 58 metres in width and 34 metres tall. In 1727 Jean-Baptiste Languet de Gergy, then priest of Saint-Sulpice, requested the construction of a gnomon in the church as part of its new construction, to help him determine the time of the equinoxes and hence of Easter.[30] A meridian line of brass was inlaid across the floor and ascending a white marble obelisk, nearly eleven metres high, at the top