WINTER rain was hammering on Pompeii the day we visited. Water sluiced down the paved streets, and gurgled in the ancient gutters. What few tourists there were huddled beneath umbrellas, their guidebooks turning to mush.

Suddenly, from a side street, there came a loud crash. We hurried to look, and found a heap of rubble and officials punching numbers on their phones. After surviving Vesuvian eruption and the passage of thousands of years, the walls of one Pompeiian house had finally succumbed to the deluge. To judge by the state of its neighbours, they wouldn’t be too far behind.

As if out of nowhere, a Rai television crew appeared, Italy’s equivalent of the BBC. The speed of their arrival showed the gravity of what had happened. With the possible exception of the Colosseum, there is no more famous heritage site in the country. And yet, as this collapse showed, it is impossible fully to preserve it. We left, pondering the future of a world-famous attraction, where hundreds of thousands of visitors pour in every year. It's hard to know whether they or the elements take a greater toll.

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To foreigners, the abundance of historic buildings in Italy is mind-boggling. I’ve often been appalled at the neglect of once-magnificent villas and fortresses that are left to moulder. When you consider how many there are, however, perhaps it’s not surprising there aren’t the funds to conserve them all.

This headache is not confined to Italy. Scotland has more than its fair share of ancient monuments and buildings of historical significance. They are an invaluable legacy, evidence of our incredibly rich and sometimes tumultuous past. Their upkeep, however, is a serious strain on the public purse. With ever-increasing footfall, and a rapidly changing climate that is wreaking havoc on stonework, there is a risk of some properties deteriorating beyond affordable repair.

Now, the director of conservation at Historic Environment Scotland, the agency in charge of the country’s built heritage, has raised the question of what lies ahead. Dr David Mitchell recently told this paper that “Everything decays and we are fighting against the ravages of time. In some instances we will have to let some go.” Among the places where difficult decisions must be made is Melrose Abbey.

Henry VIII’s army ravaged this architectural gem, along with Jedburgh, Kelso and Dryburgh abbeys, and much else. Dr Mitchell says that “Our approach has been to conserve sites like Melrose Abbey as romantic ruins, but over the past 30 years the rate of decay has accelerated to the point we are going to struggle to maintain that care and maintenance.”

The abbey’s stonework was recently found to be badly deteriorating, and other buildings are in a similarly fragile state. One such is Lochmaben Castle in Dumfries and Galloway, where it’s speculated Robert the Bruce was born (his heart in buried in Melrose Abbey). Mitchell reflects, in what sounds eerily like the conservationists’ equivalent of Do Not Resuscitate, whether HES should spend millions shoring it up, “or just let it die gracefully?”.

This dilemma is not just fiscal, but has ethical, political and practical dimensions too. Undoubtedly he is right to suggest that there has to be a national conversation about what is an increasingly urgent issue. A government body cannot and should not be left to shoulder the entire burden of conscience and accountability for our tangible heritage. Whatever policy decisions are made will affect not only us, but generations centuries down the line.

Ruins have been much in my mind recently, while writing about the locations where Mary, Queen of Scots lived and visited during her years in Scotland. Not all of them are in the care of HES, but a great many are. From Huntly Castle in Aberdeenshire to Hermitage Castle in the Borders, HES’s reach and responsibility is considerable.

Both of these castles fall into the category of well-preserved romantic ruin. With Hermitage, this adds to its menacing atmosphere, set as it is amid bleak heathland in the back of beyond. At Huntly, however, you can’t help but wish it remained in its original condition so we didn’t have to guess at the luxury in which the over-confident and over-fed Earl of Huntly lived. In this case, however, it was not time but James VI who is guilty of destroying it. Fortunately, despite using gunpowder, he left enough to allow a glimpse of its former glory.

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The author of In Ruins, the art historian Christopher Woodward, describes a ruin as “a dialogue between an incomplete reality and the imagination of the spectator.” Because of what they bring to it, everybody’s response is different.

Not surprisingly, dilapidation is particularly appealing for those with vivid – you might say overactive – imaginations. The novelist Henry James understood the irony of their appeal. On his first visit to Rome, he remarked that enjoying ruins “might appear a heartless pastime”. He sensed it hinted at a lack of empathy, rather than a surfeit: people warm to their aesthetic vintage air, rather than think of those who were bereft when they crumbled.

When it comes to Mary, Queen of Scots, do we learn more from the magnificently restored Stirling Castle than, say, the kittiwakes nesting on the stumps of Dunbar Castle? I wish I knew the answer to that. History always requires an act of creative imagining, but perhaps we relish the tumbledown because it is physical evidence of the centuries-old gulf that lies between us and those who once lived there.

Is this an argument for allowing things to decay? Absolutely not. Borderers whose abbeys and towns were attacked by English artillery probably never recovered from the shock. It is one thing for modern visitors to enjoy a ghostly outline, quite another to allow a building’s remains to turn to rubble without lifting a finger.

Sadly, though, preserving everything as it currently stands will soon not be possible. That’s what makes stewardship of the past an unenviably weighty role. HES cannot raise membership fees too high, or charge eye-watering prices for admission, for fear of putting our heritage beyond public reach. Yet if they leave nature to take its course, one can anticipate the outcry. In the end, perhaps the greatest lesson to be learned from history and its ruins is that everything – rulers, empires, and even bricks and mortar – eventually turns to dust.

Our columns are a platform for writers to express their opinions. They do not necessarily represent the views of the Herald.