Aix en Provence, St Sauveur cathedral. The Isnard organ (1724) is now essentially a colourful and elegant pre-romantic organ, somewhat remining the late (around 1830 - Utrecht cathedral...) Bätz organs, of course enclosed in its original case. Facing it on the other side is a mere façade by Isnard. Having two opposite organs was common practice in mediterranean countries. This church is however not symmetrical at all.
A novel was written about 20 years ago, where the empty façade would magically awaken and play by itself.
Df, Zeiss 25/2 @f/3.5 (I made another shot @f/2 which is nearly as sharp... with that lens, you can get anything sharp if you take care of the slight field curvature; focus plane corners are bent away from the photographer, so focussing-and-reframing is out of the question at wide apertures).