Paris - Church of Saint Sulpice. If anyone has seen/read the Divinci Code, they will recognize this church as the place where Silas murdered the nun. However, there is no "rose line" in this church. The line running trough the floor on the church is a meridian, though. It runs exactly north-south - a meridian. However, this is a larg Gnomon (sun dial). It was used to gain understanding of true mid-day in relation to the 24 hour day. This is a very precise scientific instrument which was installed in Saint Sulpice in the 18th century by astronomers of the nearby observatory, with the full support of the priest of the parish. There are several other Gnomon's in churches throughout Europe.