Up on the roof of West Yorkshire, on the handy history panels about Ovenden Moor wind farm, which whirs away 24 hours a day nearby, there is one of the most superfluous pieces of information in the world. Yorkshire Water engineers, it explains, made scientific tests of wind availability before choosing the lonely watershed between Halifax and Bradford for its 23 turbines, which feed power to 5,600 homes.
It must have taken the company half a minute, because there isn't a day out of the year's 365 when the wind doesn't have fun on the hunchbacked moor. The even more lonely stretch of Warley Moor reservoir, west of the turbines, where Halifax Sailing Club keeps a Helmand province-style bunkhouse, must hold records for both speed trials and capsizes.
Marching round the modern engineering marvel of the wind farm therefore requires you to keep an eye on the forecast, unless you relish wuthering conditions. Much of the landscape is also bleak, bordering on desolate, which a surprising number of people like; but I'd go in July or August when the heather should be purpling and the bilberries ripe.
I am out among the turbines while following a supposedly easy route: a 10km circuit, beginning and ending at Ogden Water reservoir, just north of the market town of Halifax. This is not just a wind farm experience, however. Indeed, the turbines - which are due to be replaced in the next few years by 10 even taller ones - are only the latest in a long and fascinating exploitation of what looks like biblically stony ground. You couldn't grow anything up here at over 400 metres (just over 1,300ft), but you can treat stone as a crop. Hollows, gouges and beetling quarries show where the Victorians did.
The magnificent views show the use to which they put the fine, durable sandstone. A whole sea of 19th-century reservoir dams trap water from every clough, and the distant stone terraces include the Brontë village of Haworth.
Bring binoculars. But you won't need them at the walk's beginning and end, which is an excellent place to linger in itself - a classic example of the British phenomenon of a Beauty Spot, with capital letters intended. Ogden Water reservoir is one of Yorkshire's many Little Switzerlands, a serene lake with quiet fir trees and banks of pink and white rhododendrons (well done, Yorkshire Water and Calderdale council, in avoiding the easy purple option).
The contrast between the manicured prettiness, which attracts 250,000 visitors a year, and the moors that form most of the walk is almost comical. As if to compensate for the almost unrelieved grimness of the upland scenery, Ogden has tubs of annuals, bunny rabbits flicking their white scuts at visitors' dogs and a cobbled street across the dam wall complete with a sign saying The Promenade.
The wind tends not to scour this little valley, and even on glum days there's usually an ice-cream van in the car park to supplement the vending machine at the information centre by the dam. But very soon you are on the lower slopes of Ovenden Moor, after pausing to admire a comprehensive display of dry-stone walling techniques - arches, stiles, sheep-squeezes and different ways of laying stones all in a 45-metre stretch. That's a council initiative, and useful when you start seeing the real thing, in the form of 18th-century walls near the path as it winds up Ogden Beck, buried in a beetlingly deep clough. The short version of this walk goes down some steps to a bridge just before some small but dramatic crags where, likely as not, you'll find climbers practising rope techniques.
Enjoy this bit, because there isn't any more prettiness for those doing the full walk, apart from the vast panoramas in the distance. Marching through tough-looking upland grass and Brillo pads of heather, you see Bradford to the east - shining in the sun like the Celestial City on my most recent trip - and then Keighley and the Worth Valley villages of The Railway Children to the north, when you breast the summit.
The wind farm is with you all the time, the geometry of the two wiggly lines of turbines changing all the time as you contour round. A fence prevents further inspection, but the path does come very close, at the information panels further on. The surprise for most people is the silence of the great machines (although the wind on its own more than compensates).
The return half of the circle is less dramatic, along a minor road - part of it unpaved - and a wide, stony bridleway past a closed pub, but before that comes a fine surprise. Above Little and Great Cloughs is a warren of quarries enclosing inventive shelters, pillars and unfathomable structures made of rived stone roof slates, another treasure extracted from the moor. There's even a dry-stone wall made of them, a labour of love even in a craft that normally requires the patience of a saint.
• Martin Wainwright walked route 4140 (Yorkshire's great wind farm), an "easy" 10km
