A buddy of mine did maintenance at a large chemical factory in the town where we grew up. Sometimes he would take me in after hours and show me around. It was all innocent, I just wanted to see what was going on in there.
There were a lot of impressive machines and systems but I remember being amazed by the evaporator. It was huge and it looked like something out of Willy Wonka. My friend told me that this was one of the most important pieces of equipment in the whole plant and that they called in outsider contractors to do maintenance on it. I wish that I could have seen it when it was up and running.