An iron bridge does not sound like much until you realise it was the first of its kind. In 1779, over the River Severn in Shropshire, the world's first major cast-iron bridge was completed, spanning thirty metres in a single semicircular arch, assembled with joints borrowed from carpentry. It was designed by Thomas Farnolls Pritchard and built by Abraham Darby III, whose grandfather, Abraham Darby I, had pioneered smelting iron with coke at nearby Coalbrookdale in 1709. That innovation lit the fuse of the Industrial Revolution, and the gorge that holds the works became one of its birthplaces. UNESCO listed the site in 1986.
The gorge itself is a steep, wooded valley, quite unlike the flat industrial landscape you might expect. The Severn runs in a deep cut, with trees clinging to the slopes and old kilns, foundries and warehouses scattered among them. Riding here is a mix of narrow lanes, steep hills and tight bends, and the roads that wind up from the river are often single-track with passing places, with the odd cyclist and tourist coach. The surface can be rough, and in autumn the leaves make it slippery. Visit on a weekday if you can, because the village is very busy on summer weekends.
Ironbridge has fewer than two thousand people and Broseley nearly six thousand, so fuel is best found in Broseley or the nearby new town of Telford. The bridge itself is for pedestrians only today. You can walk across the span, pay a small toll in the old days, and look down at the swirling brown water. A cluster of museums along the gorge covers iron, tiles and china, and a good visit takes a full day.
Lunch in one of the riverside cafes, then walk down to the river and look back at the bridge from the bank. The delicate curve of the iron ribs, painted in a warm reddish colour, seems to hover above the water. It is a surprisingly graceful object for something that changed the world.