Bourne Mill is a small National Trust property that rewards slow looking rather than grand expectations. The mill has Tudor origins, later industrial use, and a pretty pondside setting that makes it feel like a rural fragment tucked into Colchester.
It is best paired with a wider walk or with Colchester's Roman and medieval sights. Check opening times, because a closed mill is mostly a pleasant exterior; inside, the building's layers and machinery make the stop more worthwhile.