There is a thinning of the air, a gradual scarcity in the light. It is as though nothing has happened here for a long time and the land has folded in on itself. There is also an untidiness – an abandoned car rusting away, say, or some decaying farm buildings, or some farm machinery lying in long grass, not used for a long time. Or weeds growing wilder than usual. And a stillness, things petering out. A landscape of endings.

In the summer and autumn of 1986, I walked along the border between Northern Ireland and the Republic of Ireland. I began in Derry and ended in Louth. Ten years later I returned with a BBC producer to make a series of radio programmes. By that time there had been many changes. Some bridges had been re-built, for example, and some crossings re-opened, and there even had been some landscaping done to disguise the way in which the border, even when it was a thin invisible line, seemed to have maimed the very landscape itself. Thus the peace which came meant that some towns and villages were re-united with their hinterland.

Some of the menace in the air had disappeared. But even now, years later, the improvements seem cosmetic rather than authentic. Ninety years of partition have made too deep a difference to the landscape where Derry meets Donegal, and Fermanagh meets Leitrim and Monaghan, and Armagh meets Louth, to be easily papered over. The dividing line seems, at times, etched into the way things are; the border is, or appears, almost permanent, always palpable.

This sense of a place marked by partition is not confined to the rural landscape, although it can be very intense there. It lives also in some towns, and in the city of Derry. It is easy to see Derry as a set of enclaves, or as a palimpsest of certain events from history, including recent history. But it is hard sometimes also not to imagine what the city might look like were it, in fact, to be part of the Republic, with the postboxes green rather than red, and the Gardaí driving through it in their customary way, half easy-going, half watchful, and the atmosphere casual, almost lazy. It is as though the city leaves itself easily open to be re-imagined. In Derry, if you are facing north, you walk knowing that there are miles of normal hinterland – ordinary fields, roads, some villages – to the east, say, or to the south, but there is a sense of deadness to the west, an invisible brick wall between the city and Donegal. The line between the two places can seem as complete as the line between the land and the sea. If that were the case with Limerick or Liverpool, Waterford or Newcastle, it would give those cities a strange and edgy interest, it would offer streets full of shops, or the most ordinary supermarket car park, a special intensity. Everything re-created, both heightened and lowered, by politics, by a settlement made years before in a room with closed doors. Suddenly, in the light of this, Derry has a peculiar elusive quality, like a stage set, something specially created. Nothing can be taken for granted.

In the late 1980s, you could find, once work had ended, whole streets of the city deserted, not a single person appearing and not a sound. Not even a car. An eerie emptiness. You wondered if you were wise to be here, if you should not be indoors. And then it could break. Someone would appear, or there would be a shout or a few cars. You often wondered if you were looking for too much, if you were on your guard and thus reading tension into what was normality. It did not seem like normality.

I remember walking out of Derry towards the border on a sunny afternoon in the early summer of 1986 and slowly noticing the sense of urban decay. Nothing could thrive here. Any factory that was once here was a shell of a building now; shops were boarded up, houses abandoned. And that sense of watchfulness, imagined as much as real, and perhaps all the more powerfully present because it was hard to be sure about. If there had been a sudden sound, or a car appearing from one of the side roads, it would have been enough to stop you for a moment. Not a cause for alarm exactly; more a reason to be wary, to watch out, to be careful.

The difference between Lifford and Strabane was the difference between inertia and a strange sort of energy. Lifford seemed to have slowly emptied out, but the time span for this was long. The decline was easy to see, but hard to chart. Lifford was a place where not much moved. Strabane, on the other hand, had new roads cut through it, new systems of signposting, even some new buildings. Urban planners as much as bombers had been here. The effort to create a veneer of newness served its purpose in the same way as a shiny and noisy life-support machine can serve its purpose – it can distract from death. The energy in Strabane came from the effort to suggest energy. Once you noticed this, then the town’s lassitude was almost complete, more exact and haunting than even Lifford’s.

What is strange, of course, and easy to forget is beauty. As I moved along the border between Fermanagh and Leitrim and Monaghan, I wondered if I was misreading the landscape, if I was not looking for too much local anecdote and stories from history and irony and political copy. It might have made more sense to study the still, spare beauty of the light on a grey, cloudy morning, with the sun slanting rays of watery yellow over points in the distance. Or the extraordinary greenness of the ditches, an unkempt green especially in the Republic.

The verges and ditches tended to be more looked after, tamed, in the North. I realise that this had some sort of political significance, but there were times when the difference of colour and texture in the ditches and verges in the North and the South was worthy of study for itself alone.

If you needed politics, you could look at the difference in texture between the road surfaces. Some of this, especially when I walked north from Clones in County Monaghan, made the border almost comic. One second north and one second south. From Republic to Kingdom. Take a few steps and the Queen is Head of State, and then a few steps further, the President represents the Nation. Someone had forgotten to draw the line of the border straight, or make the road straight.

This is a landscape of intimacies as much it is as place of endings.

There are only a few motorways. There are narrow roads, some smallholdings and a feeling that people know each other and notice everything. What is strange is the level of variation.

In the borderland between Derry and Donegal and Fermanagh and Monaghan especially, there is very good land beside bogland, large well-kept farms with well-proportioned houses close to cottages and lonely bungalows. A sense of pervading ripeness versus things rotting. Nothing is easy to read in this world. Except this. On certain summer evenings when there has been rain, the clouds can move towards the horizon and the slanting sun can come out in the hour or two before darkness begins to fall. The light lifts the watery colours out of themselves into something exquisite and worthy of our full attention. These are the hours in which nothing else might seem to matter, when what has been hidden by the border, or covered by the imaginary line, comes into the open and makes itself almost clear.

Colm Tóibín

Colm Toibin’s novels include The Master (London: Picador, 2004) and Brooklyn (London: Viking, 2009), and his non-fiction work includes Homage to Barcelona (London: Simon & Schuster, 1990) and Bad Blood: A Walk Along the Irish Border (London: Vintage, 1994). His work has been translated into thirty languages. He is a member of Aosdana, Dublin and the Royal Society of Literature, London, and he is a contributing editor at the London Review of Books.