Part of a map showing the coastline of the Costa Blanca with its watchtowers. (Seen at the Museu de la Mar in Denia.)
Standing on the cliffs of the Costa Blanca today, the old stone watchtowers look quiet and almost decorative. Many hikers pass them without realizing that they once formed part of a carefully designed defensive network. In the sixteenth century the Valencian coast was not a holiday destination. It was a frontier.
Across the Mediterranean lay the ports of North Africa where Barbary corsairs operated. Their ships appeared suddenly on the horizon, raiding coastal towns, looting houses and carrying captives away to slave markets. Communities along the Spanish Mediterranean lived with the constant fear that the next sail might bring disaster.
This fear was based on repeated attacks.
One of the most dramatic occurred in 1550, when the Ottoman corsair Turgut Reis (Dragut) attacked Cullera, south of Valencia. Corsair ships landed suddenly, overwhelmed the town’s defenses, and looted the settlement. Many inhabitants were captured and taken across the Mediterranean to be sold as slaves. The attack shocked the region and reinforced the urgency of improving coastal defenses.
Further south, Villajoyosa faced a similar threat in 1538, when Barbary corsairs attempted to land and plunder the town. The inhabitants managed to resist the attack, but the event revealed how vulnerable the coast was to sudden amphibious raids. It is still remembered today in the town’s Moros y Cristianos festival.
These raids were part of a wider Mediterranean conflict. Corsair fleets connected to the Ottoman world — commanded by figures such as Hayreddin Barbarossa and his lieutenants — regularly attacked Christian coasts. Their goal was often not conquest but profit: prisoners, livestock, goods and ransom.
Spain’s response was both practical and surprisingly modern.
In 1554, the Italian military engineer Giovanni Battista Antonelli travelled more than 500 kilometers along the Valencian coast with the viceroy of the kingdom. After inspecting the shoreline he proposed a coordinated defensive system built around roughly fifty watchtowers positioned on cliffs and strategic headlands.
Drawing of the port of Moraira and a proposed watchtower for Moraira and the island of Benidorm Island, created in 1596 by the military engineer Cristóbal Antonelli. The document illustrates the planning of the coastal watchtower network built to defend the Kingdom of Valencia against Mediterranean corsair raids.
The concept was simple but effective.
Each tower had a clear line of sight to the next. When lookouts spotted suspicious ships, they lit signal fires or raised smoke signals. The warning travelled rapidly along the coast, alerting inland towns and castles. Within minutes an entire stretch of coastline could prepare for an attack.
What appear today as isolated ruins were once parts of a coastal communication network.
The project reflected the ambitions of Philip II, who invested heavily in mapping and documenting his territories. Engineers, surveyors and cartographers worked together to understand the landscape and strengthen its defenses. One of the first maps to show the system was produced in 1584 by the Flemish cartographer Abraham Ortelius, depicting the Kingdom of Valencia and its chain of coastal towers.
The towers themselves varied in shape. Some had circular bases with sloping walls designed to deflect cannon fire, while others were square. Most housed a small garrison and a signal platform from which guards scanned the horizon.
Financing such a system required substantial resources. The Crown coordinated the project, but much of the funding came from regional revenues and local communities. In Valencia, part of the money came from taxes linked to the thriving silk industry, whose trade enriched the region during the same period.
Over time the chain extended along much of the Valencian shoreline. Later maps from the seventeenth and eighteenth centuries still show more than fifty towers, demonstrating how long the system remained important.
Today many of these towers survive, scattered between modern resorts, pine forests and rocky headlands. Some have been restored, others stand as weathered fragments above the sea.
Seen from the cliffs today they may look like lonely monuments. In reality they were once the eyes and ears of an entire coastline — silent sentinels guarding a Mediterranean that was, for centuries, a pirate frontier.
