Just outside the village of Kosovelje in Slovenia’s Kras region, stonemason Mitja Kobal squints at the upper edge of a drystone wall. Crouching slightly, he eyes the position of a rough slab of limestone in relation to its neighbours and to a length of red string, which is stretched taut between two metal poles as a guideline. Then straightening up he turns the offending stone on its side, positions a chisel against a lump on its surface and gives it a series of swift, decisive whacks with a hammer, flakes of limestone spraying outwards. A small explosion of grey dust blooms lazily in the bright, late morning sun.

Originally a bricklayer, Mitja began working with drystone walls when he bought his house overlooking the Vipava Valley — a beautiful setting, with a gobsmacking view of the nearby Branik Castle, which he didn’t want to spoil by adding incongruous concrete walls. So he began restoring, and building, drystone walls around the property — a process which took him several years, by the end of which he was quite an expert. These days he’s commissioned to repair or build drystone walls — suhozidnje gradnje in Slovene — all over Slovenia and beyond.

Drystone walling is the construction of walls or other structures from stone, without using any form of binding or cement to hold them together. Its history stretches back at least as far as the Bronze Age, and in some places into the Neolithic period — halfway across Europe on the Orkney Islands, the drystone constructions of Skara Brae date back to 2,000 BC, those of Maes Howe to around 3,000 BC; and field systems buried below the peat bogs of Céide Fields in Ireland’s County Mayo are even more ancient.

The origins of this simple yet aesthetically refined and extremely durable building method probably lie in the clearing of rocks from land which was to be used for farming. The intruders were piled up in a convenient heap. You can still see these mounds of cleared rocks in fields, often no more than a jumbled pile of rubble which over the centuries has been gradually reclaimed by grass and trees — graveyards ( groblje) for stones, as Mitja describes them. In some parts of Europe, they were built into a carefully arranged stack, called a clearance cairn. In any case, these field-cleared stones were then used as building material, long before stone was quarried — to build walls, terraces, huts and other constructions.