Sheffield's industrial museum, set on a tiny man-made island in the River Don that was once the heart of the city's steel quarter. The collection covers Sheffield's industrial heritage in depth — Bessemer converters, crucible furnaces, knife-grinding wheels, and a reconstructed Victorian street of cutler's shops — but the centrepiece is the River Don Engine, a vast steam engine still run on demonstration days.
Allow at least three hours. The Cementation Furnace in the next street and the Kelham Island Tavern across the road extend the visit into a proper afternoon. Closed Saturdays; check the museum website for River Don Engine demonstration times.