James W Jardine Water Purification Plant
Everyone knows that the Great and the Good (i.e. the Well Off) in the US have a habit of getting their name on buildings by donating. I felt simultaneously sorry for James W. Jardine and pleased that he had had some connection with something so much more practically useful than, say, a University.
It turns out that this is arguably one of the biggest water treatment plants in the world - it supplies (almost?) all the drinking water for Chicago. I was impressed by the seriously high security in place around such a critical piece of infrastructure.