A renewable energy project in western Spain has led to the discovery of a remarkable prehistoric fortress believed to be more than 5,000 years old, surprising archaeologists and construction crews alike.
The discovery was made at the Casas de Hito site near Almendralejo, where workers were preparing land for a large solar power installation. What initially appeared to be an ideal location for renewable energy development soon revealed traces of an ancient civilization buried beneath the ground.
Archaeologists uncovered pottery fragments, tools, weapons and defensive structures spread across nearly 100 hectares. Excavations later identified 11 separate archaeological zones dating from around 3300 BC through the Bronze Age and into the Roman period.
The most striking find was a massive pentagonal fortress featuring an unusually sophisticated defensive layout for its time. Researchers discovered deep trenches carved directly into limestone, concentric defensive walls and carefully controlled entry points surrounding the settlement.
According to archaeologists, the structure’s five-sided geometric design provided strategic visibility across the surrounding landscape, allowing inhabitants to monitor threats from multiple directions. Experts say such polygonal symmetry is rarely seen in Neolithic Europe.
The site also contained arrowheads, tools and evidence of violent destruction, including signs of fire damage, suggesting the settlement may have faced conflict or invasion during its existence.
Researchers believe prolonged drought conditions in the region during the third millennium BC may have contributed to heightened conflict and the need for extensive fortifications.
The excavation was carried out in collaboration with Acciona Energía and local archaeologists, who described the settlement as an important power center in the Guadiana River valley during the Copper Age.
The discovery is now being regarded as one of the most significant prehistoric archaeological finds in Spain in recent years. Experts say it also highlights how modern renewable energy and infrastructure projects are increasingly uncovering hidden chapters of human history buried beneath the landscape.
Archaeologists continue to study the site to better understand the people who built the fortress and the role it played in ancient Iberian society thousands of years before modern civilization emerged in the region.