Big, flat and genuinely different from anywhere else on this list — the old concrete underfoot is a proper reminder of what the site used to be. No dogs at all here, not even on lead, since it's managed for ground-nesting birds — worth knowing before you drive out. Best between May and July for orchids and skylark song; not much reason to visit in winter.
A 600-acre former WWII airfield south-west of Cricklade, handed back to nature by Wiltshire Wildlife Trust and turned into one of the county's biggest wildflower hay meadows. Runways and perimeter tracks are still visible cracking up through the grass, and skylarks nest in numbers across the open ground.
Wiltshire Wildlife Trust reserve — free to explore on foot; many are dog-free to protect wildlife.