Marshall Field and Company, 1900
This is pretty terrific: a 1900 cross-section of the bowels of the Marshall Field flagship store on State Street. "Basement Salesroom" is the present-day lower level, which now includes housewares, the food court, candy store, etc. "The Subway" isn't the CTA, but the long-abandoned freight tunnels that weave throughout downtown. (The lower level does have access to the Red Line, via the Pedway, but the station didn't open until 1943 and thus doesn't appear here.) And it's interesting to see that the concrete caissons go down 110 feet below street level - essential to reach bedrock and support such a massive building, on what originally was marshland.