Ambleside, Cumbria
The thing children actually go for is the Grot. Sir Daniel Fleming built it in 1668 as a viewing house for Rydal Falls, and it works exactly as intended: you step into a small stone hut and the window frames a waterfall. Wordsworth came here. Your five-year-old will be more interested in the water than the literary heritage, which is fine.
The grounds are open daily throughout the year for nothing. The formal gardens are Thomas Mawson's work, all terraces and Arts and Crafts geometry, and the wider thirty-acre estate runs into woodland with sculptures scattered along the paths.
The Cafe at Rydal is on the grounds. Donations towards garden upkeep are welcomed but not collected at a gate. Parking is the one loose end, because the estate publishes no rate and warns that availability cannot always be guaranteed, so phone reception on 015394 32050 if you are coming on a fine Saturday.
Looking for more parks & outdoors near Ambleside?
The mock-gothic castle on Windermere's quiet shore, famous for its kid-friendly interior - which is exactly the bit that is closed for restoration until 2027. The grounds, lakeshore and cafe stay open and free, and arriving by boat from Ambleside is still a great small adventure.
A 70-foot waterfall ten minutes' walk from Ambleside's shops, free, and genuinely dramatic after rain. Steps, tree roots and drops mean it is a walk for legs, not buggies.