Stretham Old Engine is a former pumping engine out in the fens; visiting it is not too dissimilar to the Museum of fenland drainage that James visited a while back. You can see it from above and you can visit it’s own website: strethamoldengine.org.uk/.
It is best to visit it by boat, though, which we managed on a wednesday during the school holidays, and were even lucky enough to find it open. Sadly it is trapped in something of a vicious circle: they don’t open often so get few visitors; and since they get few visitors they can’t afford to open very often.
Pix here; and I’ll in-line a few.