South Yorkshire’s main city, Sheffield, evolved around rivers, valleys, and blast furnaces
It’s now the UK’s greenest city. In Sheffield’s Kelham Island Museum’s lofty vaulted warehouse, the sun shone in and the 425-ton, 12,000-horsepower River Don Engine, meant to roll armour plating, started up. Small puffs of steam belied its tremendous strength. I joined a crowd to witness Europe’s most powerful functioning