Lake Vyrnwy

The moment you round the bend near Welshpool and see Lake Vyrnwy properly, you understand why Victorians got so excited about engineering. This isn't some natural wonder - it's a proper Victorian reservoir, built in the 1880s as a water supply for Liverpool, and it's absolutely enormous. The lake stretches across the Powys hills like something from a Romantic painting, all reflection and drama, with a tower standing sentinel at the dam.

You can walk the perimeter - it's about seven miles if you're committed, though most visitors do shorter sections of the path. The water's clear enough to see down, and if you come early morning or late afternoon, the light does things to the surface that make phone cameras work overtime. Bird watchers get genuinely excited here; the RSPB has a visitor centre and the woodland around the edges draws warblers and woodpeckers. Kids won't necessarily be gripped for hours, but the walk's easy enough and there's something satisfying about a body of water this scale when you're standing beside it.

Access appears to be free, and you can visit year-round. Spring and autumn are probably best - summer brings the crowds, and winter can be grey and bleak. It's only a handful of miles from Welshpool, making it an easy slot into a Mid Wales holiday. If you're camped at Pandy Camping or Cae Nant Glamping nearby, you'd do worse than spending an afternoon here. Bring proper walking shoes; the paths can be muddy.