The walls that divide Menorca.

Walls that make the island

Look down from Monte Toro, or from the window of a bus crossing the centre of the island, and the first thing Menorca shows you is a grid. Fields are small, irregular in shape and almost always bounded by stone. The walls run from the road to the cliff edge and up the shallow slopes, dividing pasture from crop and one farm from the next. They are the most ordinary thing in the landscape and the thing that explains it.

The material was there to begin with. Menorca is limestone, and every field cleared for grazing or grain gave up stone. Rather than pile it in heaps, farmers laid it along the boundary, where it did a second job as a fence. Over two or three centuries of that, the island became walled from end to end. The result looks ancient and is largely practical: a field system built by hand, one stone at a time.

The walls also give the island its scale. A view that would otherwise be a long empty slope becomes a series of small rooms, each with its own light and its own shelter. From a distance the lines look like a drawing on the land, and in a way they are: a working plan of who owns what, which animals go where and which slope holds water after rain. Read them and the island stops being scenery.

Why the fields are small

The fields are small because the land is thin. Menorca is limestone, and soil collects in pockets between the rock rather than in a deep sheet. Water drains through quickly, and the wind takes more of it. Small enclosures were easier to work with animals and a plough, and easier to rest or graze in rotation. A farm here was never one field but a set of them, each with its own soil, shelter and use.

Land division reinforced the pattern. Holdings were split between heirs, and each split needed its own boundaries, so the grid grew finer with every generation. Add livestock that must be kept out of crops, and the wall becomes cheaper than a fence and impossible to blow away. Walls also hold soil on slopes, slowing what rain does to a hillside that has just been cleared. Every wall does at least two jobs, and most do three.

None of this was planned as a whole. Nobody drew the pattern. It accumulated from thousands of small decisions about where a field should end, made by people who knew the ground and had the stones at hand. That is why no two fields are the same shape and why the walls follow the land rather than the map. What looks like a design is the record of a long conversation with the terrain.

• Thin soilLimestone bedrock leaves shallow pockets of earth, so fields stay small and are worked in rotation.
• WindThe tramuntana strips moisture and soil, and a wall at the field edge slows both.
• LivestockSheep and cattle need containing, and stone is the material the farm already has.
• InheritanceLand split between heirs produced ever more boundaries, each one walled in time.

Built without mortar

A dry wall is two walls leaning together. The outer faces are built of the largest stones, laid flat and bedded so they tilt slightly inward. The space between is filled with hearting, smaller stones packed tight. At intervals a long stone runs through the full width and ties the two faces together. On top, a course of coping stones sheds water. Nothing holds the stones together except weight, friction and the skill of the person who chose them.

Building is slow, and repair is slower than it looks. A breach is not simply filled: the wall either side of it is taken down to sound work, the base is checked, and the stones are sorted before any go back. The tools are simple, a hammer to trim corners, a line for the base, and hands and eye for everything else. A wall built well stands for decades; one built badly leans within a season.

• Two facesLarge stones on the outside, tilted slightly inward so the wall grips itself.
• HeartingSmall stones packed between the faces to stop movement and spread the weight.
• Through-stonesLong stones laid across the full width to bind the two faces into one wall.
• CopingA top course of flat or upright stones that sheds rain and finishes the line.

A dry wall holds because each stone leans on its neighbours and nothing else.

Wind, salt and slope

The north coast, the Tramuntana, is the exposed side: older, darker rock, reddish sand, and wind that arrives without warning. Walls there tend to be lower and more tightly packed, built to hold rather than to impress, and the fields sit behind them in shelter. On slopes, walls are set across the fall of the land as much as along a boundary, holding soil that would otherwise wash down to the cala below.

The south, the Migjorn, is limestone, with white sand coves under pine, and the walls take a different form: thinner in places, more often marking grazing beside the coast, and built from stone that splits more easily. Both coasts show the same logic. A wall is placed where it will do the most work, whether that is keeping animals in, keeping wind out or keeping soil where it is. Look at where the lines stop and you see what the land would not allow.

The hands that build them

Much of the work was done by the farmers themselves, in the gaps between other jobs, and repaired the same way. The knowledge was local and practical: which stone splits, which belongs on a face, how to lay a corner that will hold. It passed between neighbours and within families and was learned by doing rather than taught. Some of it was done by men who made walling a trade, hired by farms that could not spare the hands.

Today the craft is thin on the ground. Few farms employ anyone full time to rebuild, and a collapsed section is often stabilised rather than restored. Training exists, run through rural organisations and the island's institutions, and volunteer repair days are organised from time to time on paths and around the natural park. If you want to know what is happening while you are on the island, the Consell Insular de Menorca is the place to ask.

Life in the joints

A wall is habitat. The gaps between stones hold moisture and shade, which is what small creatures need in a dry summer. Lizards run the top course and disappear into the joints; in Menorca these are not the Pitiusan wall lizards of Ibiza and Formentera but the island's own. Snails and insects shelter inside through the winter, and the foot of a wall stays cooler and damper than the field around it, which is why plants gather there first.

That narrow strip is also a corridor. A wall shelters seedlings, and the plants that grow along it seed into the field edge, so the boundary between two crops becomes a line of its own vegetation. Take a stone out and the structure changes: the joint opens, water gets in, frost widens the gap and the wall begins to fail. Disturbance is not neutral in a structure this finely balanced, which is why the walls are best left alone.

Reading the walls on foot

The Camí de Cavalls, the historic bridleway that circles the island for about 185 km in 20 stages, is the best way to see how the system works. The path crosses walls constantly, through gaps and gates, and each crossing shows a boundary being used rather than abandoned. Even a short stage teaches you to read the landscape: where the walls stop, the ground has become too steep, too rocky or too wet to farm.

Walkers share the path with farm animals and with the people working the land. Gates are left as you find them, closed if closed, and there is no reason to cross a wall anywhere except at a gap. In summer the interior is hot and shade is rare, and the walls give very little of it. Carry water, start early, and treat the route as a working farm track rather than a trail.

Keeping the walls standing

Menorca has been a UNESCO Biosphere Reserve since 1993, and the walls are part of what the designation protects: a landscape shaped by farming, with the coast and the marine area around it. The reserve is not a museum, and the fields are still worked. But the economics are difficult. Where grazing stops, scrub moves in, and a wall under scrub is a wall nobody repairs. Collapse follows quietly, one winter at a time.

Conservation here is unglamorous and mostly local. It means fixing a breach before it becomes a gap, cutting scrub back from a face and keeping a gate that works. It also means accepting that some walls will go. The ones that survive tend to be those with a use: along paths, around working farms, near the villages. The rest depend on whether anyone still has a reason to lift the stones back into place.

• Stay on the pathWalking the field edge compacts soil and loosens the stones at the base.
• Leave gates as foundClose a closed gate and leave an open one open; livestock depends on it.
• Never take stoneLoose stones at the foot of a wall are part of it, not spare material.
• Report damageA fallen section is easier to mend early; tell the Consell Insular de Menorca or the landowner.