What does the above photograph commemorate and document?

That's  the Ruin's of Gallego Flour Mills
 It records an event and exists as an allegory of the costs of the Civil War. Back then the Gallego flour mills were world renown and symbolize the economic strength of united states due to superior flour it produced. No-one ever thought that it would be destroyed by our own.

What i think is that it adds loudness for preachers/church choirs. it is also able to hold up a lot of weight without pillars. : )) idek tho