So cool … Tinsley Towers power station, Sheffield. Photograph: Martin Jenkinson/Alamy

The need has arisen in me to ascend my soapbox once again and bang on about public art, by which I mean street art, motorway art, art on the loose, art everywhere – which is where it belongs. Art is not a matter primarily for artists, or even curators and connoisseurs. First and foremost, it involves ways of seeing. Nothing sensible or durable will be accomplished by the four pundits who were given the job of selecting the seven sites for the current Channel 4 Big Art project if the public remains unable to see the point, or comprehend the nature of the things that will come to clutter their landscape. Artists simply do what they must, whether other people understand it or not. It is the job of critics and experts to explain what is going on. I hope someone will come along to explain to me what I should like about Mark Wallinger’s white horse sculpture, due to be raised at Ebbsfleet. Right now, I hate it.

I am hardly mollified to learn that Wallinger’s ghastly effigy is conceived as a marketing symbol-cum-landmark, and has been funded by the London and Continental Railways consortium. I hail from the land of hideous big things, all of them funded in similar ways, and all of them inspired by a soul-deep indifference to the existing landscape. At the last count, Australia (population: 21.5 million) boasted more than 50 outsize replicas of all kinds of objects, from giant apples, oranges, mangoes, pineapples and bananas to a crab, two prawns, a lobster, a galah, a koala, and a 50ft-high merino ram. These poorly designed and badly executed objects at least bear some relation to the way in which the locals earn their living. If Wallinger’s white horse has any relevance at all, it is as a presager of death, as pale horses tend to be in northern mythologies. This way to the knacker’s yard, folks.

Before people can comprehend the newness of a new thing, they need to be awakened to the extraordinariness of the old. All over Britain monuments of the recent industrial past are being demolished. Gasworks have been pulverised to make hard core for supermarket car parks. Gas holders, those vast pachyderms that once loomed over the murk and mist of all our old industrial precincts, have been dragged down and carted away. Only 22 were ever listed for preservation; Transco has since demolished all the others. The seven surviving gas holders at St Pancras were decommissioned in 1999, to make way for the Channel tunnel rail link terminal. All but four have since been demolished (the other four are listed). The uncharacteristically ornate frame of Gas Holder 8 is to be taken down, restored and re-erected as a setting for open-air events, so it will be a gas holder no longer. The other three, the famous linked-together triplets, have already been dismantled, with a view to restoration, and re-erection, again of the frames only, with new-build apartment blocks inside them. This is what passes for preservation in the case of gas holders.

Cooling towers are even more fabulous creatures. Their hugeness, 400ft or so high, already approaches the sublime, even before we notice that with every change in our ever-changing light, they appear different: less or more substantial, lowering or floating. Those who have to live amid them may feel different, much as a pebble would do under a jackboot; the solution is not to wish the towers away, but to build better housing in a place out of their shadow. Nowadays, cooling towers seldom wear their plumes of cloud; we don’t often see their whirling shadow patterns on their great grey flanks. I’d pump hot water into them for high days and holidays – much as we run the most extravagant fountains only when there’s something to celebrate. I would even allow the projection of images on to the towers and their steam clouds as part of the fun, at a pinch.

The Tinsley cooling towers in Sheffield were not among my favourites, mainly because of their girdles of finicking detail; but they were real wonders to be experienced by the people flying past on the M1. The horizontality of the suspended Tinsley viaduct, and the extreme mobility of the passing vehicles, dramatised the stillness of the hulking towers in a uniquely thrilling way. The towers were already art objects, and shouldn’t have had to be falsified to function as art galleries and cafes or whatever else. Their uselessness is an essential part of the role of art object. Nevertheless, their suitability for transformation into something else – a skate park, a pair of giant tankards – had them top of the national vote for sites for the Channel 4 Big Art project. Last August, possession being at least nine-tenths of the law, E.ON UK, owners of the Tinsley towers, blew them up.

When local authorities announce their intention of taking down dangerously senescent street trees, citizens hit the streets demanding a stay of execution, as if death were not as inevitable for trees as it is for us. Those same people, who cannot tell a sick tree when they see one, see nothing to love in the extraordinary human-made devices that made the 20th century possible. These will not come again from seed. When they are gone, they are gone for ever.

Germaine Greer