Gervais and Protais, two brothers martyred under Nero, well deserved their church. It was completed in 1657 and is built on a slight elevation, which is further accentuated by the steps of the classical entrance. Inside, the organ, built in 1601, is the oldest in Paris. It was played from 1656 to 1826 by eight members of the Couperin dynasty. The church is gradually replacing its white glass windows for modern stained-glass creations by Sylvie Gaudin and Claude Courageux.