Dubi Gan: You recognize this strange device as a mechanical heart, meant to be used by a golem. There was a fad about a 1000 years ago to make golem more "organic" with magical fluids pumping through carefully made veins etc. This fell out of favor, but the item still has some value.
If you were to break it and strip it for the precious metals, you could probably get a few hundred rupees. If it was sold intact at an auction (slugmen love auctions) it would sell for more. If you could find the right buyer (a golemologist interested in this topic)… a few thousand rupees wouldn't be out of the question.
The least lucrative option would be to turn it over to the previous owner (the House of Wind) for a small reward, but it would put you in the good grace of a minor Noble House, which is something.
I will note – you did research specifically on this! - that objects found in the Old City are "finders keepers", by Yellow City Law. So legaly speaking, you don't have to return it.
In brief, you definitely found treasure.