Chris, I see you have got your library card.
DPL's Sanborn maps are a great resource. They are even more stunning when you realize they are all hand drawn and colored with watercolor--and in many cases even updated. Of great note are all the details inside the building footprint, like the boilers. For those not in the know, Sanborn was an INSURANCE company, and they deeply cared about limiting their risk, particularly of fire. Hence the notes like, "no exposure any side," which is code for, "if this catches on fire, it will not harm other buildings."
I love the notation for the water wheel and trace, "Vac" indicates vacant, and the notes about operation, which implies someone is on duty in the event fire breaks out.
"IR CL" indicates 'iron cladding' which would resist catching fire from air borne cinders. Note that there is a thicker outline where this occurs.
All reasons why Sanborn Maps are great modeling resources!
Keith Hayes
Leadville in Sn3