Ok, apologies for 3 consecutive messages:
http://www.bostonplans.org/getattachment/5222d0e4-7e1f-4384-bd4f-c13ed9f91b7c
P. 71 clearly shows a reconfigured Fargo St. turn. So your instincts were right! (Sorry no screenshot capability at the moment, maybe someone can grab it and post it..)
And in the process of reviewing the plans, I noticed that the low-rise section across the middle of this bad boy actually appears to act as a big truss that holds up the ceiling of the massive ballroom(s) below it? And if that's the case it seems likely that there is probably also some lateral extension of that truss function all the way over the to the Fargo St. corner...
But as I said I'm definitely an amateur so I'll look forward to hearing from you pros on this too...