Garreg Ddu Dam

The curve of Garreg Ddu Dam rises out of the Elan Valley like something from a Victorian engineering manual - because it is one. Built in 1894, this pale stone structure was part of an ambitious water scheme to supply Birmingham, and it's genuinely impressive when you stand before it. The reservoir it creates stretches into the hills, and the whole valley has a wild, reservoir-scape quality that feels properly Welsh.

You walk right up to the dam itself - no entry fees, no barriers, no nonsense. The best light comes late afternoon when the stone glows. From the top you get views down the valley and across the water to the other dams (there are four altogether in the Elan Valley, built in sequence). Most people allow thirty minutes to an hour, though walkers often use it as a starting point for longer routes around the valley floor.

It suits two types: heritage enthusiasts who appreciate Victorian industrial architecture, and walkers who want genuine hills without the Snowdonia crowds. Kids will find it a bit static unless they're the sort who enjoy spotting water birds and scrambling on rocks. Rhayader sits just a few miles downhill and makes the obvious base.

The nearby caravan parks - Elan Oaks is closest at two miles - all sit within striking distance of this whole valley network. If you're camping in the area, the dam is a simple morning jaunt before heading out on longer trails. Worth the detour if you're already in Powys, though it's not quite dramatic enough to justify a special trip on its own.