The First Iron Bridge — and the Fortune It Cost the Man Who Built It

In 1779, they cast the world's first iron bridge — and no one was sure it would hold.

For all of history, bridges meant wood or stone — iron was for pots and cannons. Architect Thomas Pritchard designed it, and ironmaster Abraham Darby III gambled his fortune casting it from iron.

Work began in 1777. Nearly 400 tonnes of cast iron were fitted together with no bolts and no mortar. No one had ever joined iron this way, so they borrowed carpentry joints — dovetails and mortise-and-tenon. Until the scaffolding came down, no one knew if it would hold.

It held — and it stunned the world. Travellers called it one of the wonders of the age, and artists came to paint it. But it ruined Darby: the bridge cost nearly double the estimate, and he spent the rest of his life in debt.

And it's still standing, 250 years later. The Iron Bridge proved iron could carry the weight of a new world — the blueprint for the railways, factories, and skyscrapers that followed.

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