There is a story that one abutment of this bridge moved dramatically when it was decentred, requiring a lot of expensive remedial work. The sag is visible so it seems likely that the story is true, but where did I see it?

Ballochmyle Viaduct, the largest arch on the British Railway system!

John Millar designed the Glasgow and South West Railway, which eventually was joined from Dumfries to Gretna Green to form an extension of the Settle Carlisle. Ballochmyle was a huge undertaking, but there are many big bridges on the line.

Designed by Stephen Ballard in 1843 to take a minor (no through) road over the Hereford to Gloucester Canal. If you want to go and see it you could stay with his great-grand-daughter at Old Country House. That's how I was introduced to this remarkable bridge.

On the A470, on the southern exit from Llanelltyd, the bridge crosses Afon Mawddach. It has been bypassed by a modern bridge which will surely be gone long before this one. It is a scheduled monument dated to the second quarter of the 18th Century.