ON a low ridge above Loch Roag, the Stones of Callanish emerge portentously from ancient peat, exuding an air of magic and mystery. Known also now as the Calanais Stones, these megaliths are right Neolithic, that is to say 5,000 years old, and are said by many to form the most famous prehistoric site in Scotland.

They stand near the township of Calanais, 13 miles west of Stornoway on the island of Lewis, and nobody really knows what they were for. That said, many authorities accept that their purpose was astronomical, probably in association with gruesome rituals spectacularly performed in pursuit of religious beliefs which were almost certainly stupid. But, hey, what do I know?

I have my own astronomical tale to tell you about Callanish. After completing an assignment in Lewis, I went with “my” photographer to see the stones. He claimed insider knowledge about a full Moon rising that evening.

Photographers always had far better equipment – such as fab laptops – than reporters, who were generally furnished with a pencil and a Gideon’s Bible. You can imagine how impressed I was when my colleague said he’d got his info from Nasa. By which he meant off the internet, which was relatively new then.

READ MORE RAB: ‘Is this a dagger which I see before me?’ Don’t know. You tell me, mate'

Unfortunately, his info was wrong. Well, due to Britain’s time differences with everyone else, it was out by an hour. So, leaving the only other visitors – some hippies – waiting forlornly at the site, we wandered off for an hour and, when we returned, witnessed the most spectacular astronomical sight I’ve ever seen (after the Northern Lights): a huge red moon rising above the stones.

The hippies had gone, and we were the only ones there, standing awe-struck in the shadows, feeling about two inches tall. I remember thinking how fast the Moon seemed to be going. Maybe it had other stone circles to visit that night.

I’ve no idea if it was aligned with the stones. Critics of such astronomical theories aver that any such alignments probably exist by chance. They remind me of these diagrams in post-match analyses of the football, where lines are drawn between player A, player B and the pie-stand, supposedly showing some kind of tactic. But you can draw lines between anything.

A more probable explanation is that the stones represent petrified giants, “the false men (na fir bhrèige)”, who refused to convert to Christianity. Another legend holds that, on midsummer morning, a weird being known as the “Shining One” walks the length of the avenue, heralded by the call of a cuckoo, which sounds curiously appropriate.

What exactly are we talking about? I was hoping nobody would ask that. Oh, I see: you want a description. Well, it’s some stones standin’ aboot. That’s all I could see anyway. But, again mea culpa, this reminds me of the football, where folk say: “They’ve moved from a flat back four to a three-five-two.” And all I can see is a bunch of folk running hither and yon.

In truth, there was method in their megaliths. The aforementioned “avenue”, at 90 yards nearly the length of a football pitch, narrowed in towards the central stone circle and 15-ft monolith (weighing seven tonnes) at the heart of the monument, suggesting a route for processions.

READ MORE RAB: A trade offers a greater degree of usefulness than Uni

Smaller stone-lined pathways radiated east, west and south, making a cruciform pattern. A small chambered tomb sits within the stone circle, though this is of later date. Forty-nine stones, all of local Lewis gneiss – gneiss stuff when you can get it – stand on the site today.

It’s not known how many were erected originally. One estimate says 80, though excavations have revealed only one other empty socket.

There are at least 11 smaller stone circles, arcs and alignments within a six-miles radius of Calanais, some dating from much later than the central circle, as sell as numerous single standing stones. Back in the day, you couldn’t turn round without tripping over a standing stone.

The Calanais stones were erected between 2900 and 2600 BC, predating Stonehenge with its relatively modern brutalist architecture, and may have been a focus of ritual activity for 2000 years, since progress was painfully slow back then.

Around 1500-1000 BC, the site fell out of use and became buried in a build-up of peat, disappearing and then reappearing briefly for new use, possibly domestic. By the 19th century, only the tops remained and it was not until 1857 that they re-emerged towards their full height when James Matheson, the “proprietor” of Lewis, ordered five feet of peat to be cut from them.

In 1885, the stones were taken into state care as a valued monument and, today, they are managed by Historic Environment Scotland (HES), which surprisingly doesn’t charge visitors to see them, probably because it doesn’t know what to do with all the loot already robbed from tourists at Edinburgh Castle.

Today, there’s a “visitor centre” at the site, with a cafe, shop and “Story of the Stones” exhibition run by community-based trust Urras nan Tursachan, whose research (to be fair) is supported by HES. Entrance to the exhibition is £3.50 (£2.80 concessions), which is pretty reasonable.

How to end the “story of the stones”? Well, the stones speak today, says HES, “of a thriving and sophisticated society” from the past, one with a warmer climate than today and plentiful wildlife and food sources.

Neither was it insular, but almost certainly part of a wider culture with which it shared rituals and knowledge, even if much of it was daft. Pottery finds suggest links with Orkney in particular.

Today, the presence of modern houses and roads in the surrounding area does little to dent the timeless, elemental feeling of the site, set amidst a rugged, sea-girt landscape brooding under vast and ever-changing skies.

If you’ve a cuckoo about your person, maybe you could process down the “avenue” in peculiar robes to relive the full Callanish experience, for which I would recommend also a huge red Moon (timetable available from Nasa).