This is a new topic for me. When I hear “pantheon”, my mind jumps to Rome.
But Paris has its Pantheon as well, and it is a world unto itself.
Listening to the pianist gave me a perfect opportunity to make a quick video of the entire panorama.
The Parisian Pantheon, the exterior
get back, lauretta! 
But who would drag a piano around Paris. looking for likely venues? Only in Paris.
I had the same thought! Must be a studio nearby that it’s fairly easy to roll out to this Place!