This is as close as I could get to Église Saint-Ephren Le-Syriaque and had to shoot from behind the iron gates.
As you can see from the poster this church is often filled with music and is known for its classical concerts. According to the signs, there is a regular Mass on Sundays. The first church edifice was built here in 1334, the second in 1685, and the one standing on the site today is the third built in 1733.
Here is a link to the concert schedule for 2012.
Église Saint-Ephrem Le-Syriaque
15, rue des Carmes