I think I was able to make sense of this. This used to be the main building outline, but it has been shrunk a bit to represent the line where the building touches the "plaza". A new way was drawn for the widest extension of the arena. It looks like there were a few tags left over on the old line. 
Now, I made a MP for the arena building using the widest outline and the hole in the roof. The main tags should go there. I also added "note" tags to some of the elements so others can understand whats going on better.