Claerwen Dam

You'll round a bend in the Elan Valley and suddenly there it is - a massive curved wall of concrete holding back an impossible amount of water. Claerwen Dam is one of those structures that stops you mid-drive. Built in 1952, it's the youngest of the four dams that make up this Victorian engineering marvel, and it genuinely impresses even if you're not usually moved by civil works.

The dam itself is free to visit and you can drive right up to it or walk across the top - the views into the valley below are properly striking, especially on overcast days when the water looks dark and serious. There's something about standing on top of a dam that high that makes your stomach lurch a bit. The whole valley is a water engineer's fever dream: you've got Claerwen holding court, but also Caban Coch, Pengarreg, and Garreg-ddu all within a few miles, each with their own drama.

Walkers will find this area excellent - you can do shorter loops around individual reservoirs or tackle longer circuits that link them. Allow anything from an hour for a quick visit to half a day if you're combining it with nearby trails. Families with young kids might get restless after 20 minutes unless they're into massive water structures, but older children who like hiking will rate it.

Base yourself at Elan Oaks Camping or Welsh Glamping - both are close by - and you can explore the whole valley across a few days. Llanwrtyd Wells is the nearest proper town for supplies, about 15 minutes' drive away. Go early morning if you want the place to yourself.