Twizel Viaduct

The viaduct looms suddenly as you round the bend near Coldstream - a proper Victorian engineering statement in stone that makes you stop and stare. Built in the 1870s to carry the railway across the Tweed Valley, it's one of those structures that feels genuinely impressive without being fussy about it. Thirteen arches stride across the valley floor, and the stonework has weathered into this beautiful soft grey that photographs brilliantly in late afternoon light.

You can walk underneath if you're feeling adventurous, or park up on the road and take in the whole span from a distance. It's not a destination that'll eat up your afternoon - you're looking at twenty minutes to half an hour realistically - but it's exactly the sort of Victorian engineering marvel that makes the Scottish Borders worth the detour. History enthusiasts and photographers will get more from it than others, if I'm honest.

The nearest proper base is Coldstream, just a few miles down the road, and Coldstream Holiday Park makes a solid stopping point if you're doing a broader tour of the region. The viaduct sits nicely between a valley walk and a drive through some genuinely lovely border country. Bring a decent camera or just your eyes - either way, it's worth pulling over for.