Stone towers above the sea.

Why the towers were built

For several centuries the coast of Ibiza was a frontier. Raids by corsairs from North Africa and further east were a fact of life, and much of the population lived inland or behind walls. A sailing ship sighted off the coast gave very little warning. From the sixteenth century the island's councils and the military engineers of the day answered with a line of stone towers, set where the view ran furthest over the water.

Most of the towers still standing date from the second half of the sixteenth century, when the defences of the island were reviewed and rebuilt after serious attacks. The plans were simple: round towers with thick walls, small garrisons and no door at ground level. They were not forts. Their task was to see and to tell, not to hold a landing, and they were never meant to stand alone.

How a signal travelled

Each tower kept a watch on a stretch of sea and on the next tower along the coast. A watchman who saw sails raised smoke by day and fire by night. The tower to the north or south answered and passed the message on, so that word reached the town below Dalt Vila while a ship was still offshore. The system was simple and quick, and it lasted as long as the raids did.

The same towers watched over the salt pans, the fishing coves and the paths between them. Some later served as lighthouses, signal stations or plain landmarks for boats. What remains is the shell of a practical idea: sightlines chosen with care, on headlands where the wind is constant and the view runs a long way in both directions. The siting has survived better than the masonry.

A watchman who saw sails raised smoke by day and fire by night.

What a tower looks like

Stand close to one and the design explains itself. The walls are thick and slightly battered at the base, built of local limestone, sometimes with a course of darker stone. There is no door at ground level: entry was by a ladder to a gap above the reach of anyone standing below, pulled up behind. Inside, a small vaulted room held a handful of men, water and a little powder.

Around the top runs a parapet with openings for looking out, and often a low platform where the fire was lit. Many towers are round; a few are square, or built onto older structures. Almost all stand on private land or inside a protected area, which is why some are rough underfoot and access differs from one to the next. Where a tower has been consolidated, the work is usually minimal: repointed stone, a path, a sign.

• The doorSet high in the wall, reached by a ladder that could be drawn up.
• The parapetOpenings for watching and signalling, low enough to shelter behind.
• The vaultA single stone room, cool in summer, that held a small garrison.
• The sitingHeadlands and points where the next tower stays in sight.

Torre des Savinar and the cliffs

Torre des Savinar, the tower above Cala d'Hort, is the one most visitors see. It stands near the edge of the drop, with Es Vedrà and its smaller neighbours straight ahead and the sea below. The walk from the road is short and level enough for most people, and the reward is a view of the south-west coast that takes in the whole shape of the island's edge.

This is also a place to take care. The cliff path has no railings, the rock is loose in places, the wind is stronger than it looks from the beach, and the light goes early in winter. Parking near Cala d'Hort is limited and fills quickly in summer. Es Vedrà is a nature reserve with no landing, so the tower is the closest most visitors will get to it.

The towers of the west

On the west coast the towers face the sunset, and that is how most people meet them. One stands on the point above Cala Comte, above the small coves and the flat rock shelves where people swim. In the evening the path up is busy, and the view west runs clear to the horizon with nothing in the way. It is a good place to watch the light go, and an easy one to reach.

The west coast also had the most to lose. The towers here kept watch over the coves where small boats could land, and over the paths that carried goods inland. Some are now on walks used by many, others stand behind walls on private land with no access at all. A drive or a long walk along this coast passes several, and the difference in condition is easy to see.

Portinatx and the north

In the north the coast is steeper and the towers sit above pine and rock rather than sand. One overlooks Portinatx, on a point between the coves, and the walk up is short from the village. The view takes in the whole bay, the islets offshore and, on a clear day, the coast running south. The water below is cooler and clearer here, and the rocks are good for swimming when the sea is calm.

The north has fewer visitors and fewer facilities. Paths are rougher, shade is thinner, and a car is useful for reaching the starting points. In return the towers here are usually quiet. The sense of a working coast, with small boats, dry stone walls and terraces cut into the slope, has survived better than in the south. What the towers see now is mostly weather: wind from the north, the same headlands, very few sails.

The salt route at Ses Portes

The tower at Ses Portes stands between the salt pans and the sea, on the narrow strip of land that separates the two. From it the watch ran over the salinas, the channel and the beaches to the north. Salt was the island's oldest export and worth guarding; the pans, the storehouses and the boats that carried the crop were all within sight of this point. It is a low, plain building, easy to miss from the road.

Walking here is easy and flat, on tracks between the salt pans and the dunes. Birds are the other reason to come: the pans and the shallow water behind the beaches draw waders and flamingos at the right season. The tower is a small ruin now, but the position makes the old logic obvious, with a clear line of sight north and south along the coast. In summer the pans shine; in winter they are grey and quiet.

• The salinasShallow pans where salt is still harvested, worked in squares of pink and white.
• The channelWater moves between the open sea and the pans through a narrow cut.
• The birdsWaders and flamingos use the shallow water, especially on migration.
• The dunesLow sand hills and juniper behind the beach, held in place by roots.

Visiting the towers today

Most towers are a short walk from a road, and access varies. Some stand in protected areas with marked paths, some on private land where walkers are tolerated, and a few are effectively closed. Walking guides for the island list those that can be visited, and the councils publish access information for the protected areas. Check before setting out, especially in summer, when fire risk can close paths. A tower seen from a distance, with the coast around it, is often the better half of the visit.

Go early or late. The towers stand in the open, with little shade and no facilities, and the middle of a summer day is punishing. Take water, wear shoes with grip, and keep away from the edge when the wind is up. Out of season the same places are empty and the light is better, though some seasonal tracks and car parks are closed and the gates of protected areas keep their own hours.

• WaterThere is little shade on the headlands; carry more than seems necessary.
• ShoesRough limestone and loose gravel reward shoes with a proper sole.
• TimingEarly morning or the last hours of light, not the heat of the day.
• MapsA paper or offline map helps; coverage can be thin on the cliffs.