The Saint Paul Saint Louis Church is found in the Marais very near the metro stop. Saint Louis was actually King Louis IX, a very religious king who was made a saint, thus the name of the church. You can find an engraving of him there.
Up high in the dome is a sun, the symbol of the French kings. New since the last time I was there, were the decorative items hanging from the dome. I wasn’t sure what there were-either clouds or snowflakes I think.