Three bridges in a row: Telford, Stephenson and the road that came after

There is a spot on Telford's bridge, about a third of the way across, where you can see three river crossings at once and put a date to each of them. It is not a famous view and there is no interpretation board pointing it out. It is, for anyone who cares how things get built, the best twenty minutes in Conwy.

1826: Telford, and a bridge that argues with a castle

Thomas Telford built the Conwy Suspension Bridge between 1822 and 1826, to carry the London to Holyhead mail road across a river that until then meant a ferry and a wait. The span is 99.5 metres. What makes it worth standing on is a decision Telford did not have to make: he shaped the towers to answer the castle they land beside, castellated, in the same grey stone, so that a piece of 1820s iron engineering deliberately defers to a piece of 1280s military engineering. It is not a pastiche and it is not a disguise. It is one engineer acknowledging another across five and a half centuries.

The bridge carried road traffic until 13 December 1958, when the modern road bridge opened alongside it. The National Trust has owned it since 1965, and it is now open to pedestrians and cyclists, with the toll house at the far end. 2026 is its bicentenary, and Conwy Town Council held a Telford 200 parade to mark it on 27 July.

1849: Stephenson, and a box you can run a train through

Twenty-three years later, Robert Stephenson put a railway across the same gap and solved it a completely different way. Working with William Fairbairn and Eaton Hodgkinson, he built a wrought-iron tubular bridge: two rectangular box-section tubes, each about 129 metres long and four and a half metres wide, assembled using shipbuilding methods and weighing something in the order of 1,300 tonnes apiece, with the trains running inside them rather than on top. The first tube took traffic in April 1848 and the bridge was officially opened in 1849.

Conwy was the rehearsal. Stephenson needed to prove the tubular principle before committing to the far larger Britannia Bridge over the Menai Strait, and this is where he proved it. The postscript is why the Conwy bridge matters more now than it did then: the Britannia was badly damaged by fire in 1970 and rebuilt as a truss arch, which leaves Conwy as the only surviving Stephenson tubular bridge anywhere. It is Grade I listed, it is a scheduled monument, and Network Rail still runs trains through it every day. You will go through it yourself if you arrive by train from the Chester direction, and you will not notice, which is somehow the point.

1958: the road bridge, and why nobody photographs it

The third crossing opened on 13 December 1958 and took the traffic off Telford's chains. It is the one visitors edit out of the picture, and it is the one that made the other two into monuments rather than infrastructure. Worth a glance for that alone.

And the fourth crossing, which you cannot see

The A55 does not use any of them. The north Wales expressway goes underneath the estuary through the Conwy tunnel, and the spoil dug out to build it was not carted away: it was placed on the far bank, and it is now RSPB Conwy, a reserve of lagoons, reedbed, grassland and saltmarsh holding waders and waterbirds from August to March and tens of thousands of roosting starlings in winter. A road tunnel that produced a nature reserve is a genuinely unusual by-product, and the reserve is about 1.6km from the walled town, walkable over the road bridge in around twenty-five minutes.

How to see all of it in an afternoon

Walk out onto Telford's bridge from the castle end, then turn once. Upstream, to the south, it is chains and then tube: Stephenson's tubes sit about thirty metres further up the river. The 1958 road bridge is the other way, downstream toward the estuary, about the same distance behind you. The whole sequence spans less than seventy metres of water. The National Trust lists the bridge as open to pedestrians and cyclists; toll house opening is separate and seasonal, so check the property page if you want inside it. Then either continue across and follow the far bank to RSPB Conwy, or come back and climb the castle's battlements, from which the whole sequence lines up below you in one frame.

Take a windproof layer. The bridge sits square across the estuary mouth with nothing between it and the Irish Sea, and it is reliably the coldest twenty minutes of a Conwy day, in July as much as in January.