The
Gnomon of Saint-Sulpice is an
astronomical measurement device located in the
Church of Saint-Sulpice (
Église Saint-Sulpice) in
Paris, France. It is a
gnomon, a device designed to cast a shadow on the ground in order to determine the position of the sun in the sky. In early modern times, other gnomons were also built in several Italian and French churches in order to better calculate astronomical events. Those churches are
Santa Maria del Fiore in
Florence,
San Petronio in
Bologna, and the Church of the Certosa in
Rome. These gnomons ultimately fell into disuse with the advent of powerful
telescopes.