The St Francis de Sales School for African American girls was founded in 1899. After graduating over 5,000 young ladies the school closed in the early 1970s. Now the building is crumbling and mostly inaccessible except for this nave. I don't know much about this school, more information is available from John Plashal who has a YouTube Channel and does PodCasts that include at least one about St Francis. This image from the choir loft at the back of the room.