The Church of Saint-Sulpice is a Roman Catholic Church in the Latin Quarter. It is the second largest church in Paris, behind Notre Dame. Inside the church you will find an 18th century astronomical device, called the 'Gnomon of Saint-Sulpice', which was used to determine the position of the sun, based on a shadow cast on the ground. Dan Brown, the author of The Da Vinci Code gave it an occult meaning, describing it as a 'pagan astronomical device', and tracing it back to a 'pagan temple' which once stood on the same spot as the church.