Temple Square on Main Street before leaving for their missions. The Conference Center currently occupies the area where there was a parking lot and the Mission Home and some other buildings. Anyway, at that time the missionaries would go through the temple and then be taken up to that assembly room for a question-answer session with several General Authorities. There are tiered stands similar to those you see in the Kirtland Temple at either end of the assembly room, with one end representing the Melchizedek Priesthood and the other representing the Aaronic. Yes, the room is large. I don't remember for sure, but it seems as though it took up the entire floor.