At Sacyr, protecting archaeological heritage is part of the way we deliver our projects. 

We work to safeguard historical finds and heritage assets wherever they appear. This commitment is also reflected in our training: in 2025, our professionals completed more than 3,700 hours of awareness programs on heritage preservation. 

These five recent projects show how we help protect the historical and cultural memory of the communities where we work. 

Almudévar Reservoir (Huesca, Spain) 

During construction of the Almudévar Reservoir, we recovered the remains of the south wall of the former Santo Domingo Hermitage, dating from the 12th and 13th centuries, and relocated it stone by stone. 

The wall is now part of the new hermitage, preserving the structure and keeping the site’s historical story alive. 

High-Speed Rail Line in Almería (Spain) 

Around Almería’s former railway station, we identified a concentration of finds suggesting the presence of an Islamic settlement, including abundant ceramics and hydraulic structures. The importance of these discoveries prompted a review of the heritage protection boundaries established in the urban planning framework. 

We also documented remains of Spanish Civil War air-raid shelters, including the so-called “workshops shelter” beneath the station’s former canopies. Although its condition made preservation impossible, it was recorded through 3D scanning and photography, and a commemorative marker was installed to preserve its memory. 

Loja Bypass, Antequera-Granada High-Speed Rail Line (Spain) 

In this project, we documented an extensive archaeological area around the site known as “Cerro de la Estación.” The preventive archaeological work allowed us to excavate more than 5,000 m² and identify dozens of structures, including pits, silos, and burial sites. The volume and spread of the remains meant the initially planned protection perimeter had to be expanded, contributing both to scientific knowledge and to the safeguarding of the site. 

Test excavations confirmed the presence of archaeological structures from periods spanning the Neolithic and the final stage of the Stone Age through to Late Antiquity, in the 5th century AD. 

The work documented Neolithic silos and burials, as well as rooms belonging to a Roman villa, together with a large quantity of archaeological material. 

Ibiza Wastewater Treatment Plant (Spain) 

The Ibiza Wastewater Treatment Plant project revealed a Roman road, a 16th-century irrigation channel, a Roman aqueduct and a Phoenician archaeological site of significant heritage value. Wall structures, a hydraulic structure, amphorae and a well were also found. 

“Taking part in this project was particularly interesting from both a technical and heritage perspective, as the works revealed a broad and diverse archaeological context,” explains Cristina Alonso Comba, site manager for the wastewater treatment plant. 

From a construction standpoint, this posed a major challenge. Construction solutions had to be continuously adapted so the project could move forward while preserving the most valuable elements. In some areas, the alignment and gradient were adjusted; in others, pipe jacking was used to protect significant structures and avoid direct impact. 

The archaeological remains and materials were handed over to the Museu Arqueològic d’Eivissa i Formentera for study and cataloging. 

Railway adaptation works in Mato Miranda (Portugal) 

In Mato de Miranda and Arneiro das Malhadas, we found a range of archaeological materials from the Late Neolithic or Chalcolithic period, including ceramic fragments, lithic artifacts, and remains of ancient domestic occupations. Found during archaeological monitoring of the work, these discoveries offer new insight into how this territory was inhabited over time. 

The ceramic fragments and lithic artifacts were handed over to Portugal’s Direção Geral do Património Cultural. 

Would you like to know more about how we protect the places where we operate? Read our Natural Capital Report 

MARÍA GÓMEZ BRAVO | Tungsteno

In the Nile Delta, many ancient Egyptian cities disappeared centuries ago beneath layers of sediment, farmland and modern development. From ground level, they are almost impossible to identify. Seen from space, however, some leave faint traces in the form of geometric lines, tonal variations or slight differences in soil moisture. Sarah Parcak, an Egyptologist and professor at the University of Alabama at Birmingham, has turned these subtle signals into a tool for locating potential archaeological sites without the need for prior excavation.

In the early 2010s, she participated in a number of projects focusing on ancient Egyptian settlements. In the Nile Delta, the contrast between cultivated land and desert areas makes it easier to detect small changes in the terrain that are invisible to the naked eye. Satellite imagery revealed geometric lines and subtle surface variations that corresponded to buried ancient structures. These were not visible ruins or cities emerging from the sand, but rather physical traces that the landscape had preserved for centuries.

Parcak began working with this type of imagery during her doctoral research at the University of Cambridge. Unlike conventional photographs, multispectral images capture information that the human eye cannot perceive. Her aim was to locate tells—mounds formed by successive layers of human occupation—and possible buried structures across the Middle East based on these minute alterations detected through infrared sensors. “To try to map the past, I have to look at it in a different way,” Parcak has said, summarising a central idea that runs through her research: landscapes preserve physical evidence of the people who inhabited them centuries ago.

Sarah Parcak explains how space archaeology uses satellite imagery to locate traces of ancient civilisations hidden beneath the ground. Credit: TED.

A new way of interpreting the landscape

The use of aerial imagery to study the terrain was not entirely new. After the First World War, photographs taken from military aircraft began to reveal ancient shapes and structures that were difficult to identify from the ground. Decades later, satellites from NASA’s Landsat programme made it possible to extend this observation to vast swathes of the planet and analyse how landscapes changed over time. But the real breakthrough lies not in conventional photography, but in understanding how buried structures affect soil, vegetation and temperature.

For example, a buried wall can alter the moisture content of the soil above it. Similarly, an adobe structure can change soil compaction and affect vegetation growth. Some constructions also generate temperature differences that become detectable at specific times of day. By analysing these subtle variations, researchers can identify areas with archaeological potential, which must then be investigated on the ground. Parcak herself insists that these tools do not replace excavation, but rather help to guide and focus archaeological fieldwork.

From isolated sites to landscape-scale analysis

The ability to analyse entire regions rather than just specific sites is one of the main contributions of this methodology. One of the best-known examples is the work carried out at Tanis, an ancient Egyptian city located in the northeastern Nile Delta. Although the site had been known for decades, satellite imagery helped researchers reconstruct parts of its buried urban layout, revealing streets, structures and occupation zones hidden beneath sediment and modern agricultural land.

The value of this type of research lies in understanding how ancient urban and agricultural landscapes were organised on a large scale. Parcak applied this same approach to the study of the funerary complexes and tombs of El-Lisht, one of the principal centres of Egypt’s Middle Kingdom, as well as to Petra in Jordan. There, she identified a monumental structure that had gone unnoticed despite Petra being one of the most intensively studied archaeological sites in the world.

This shift in perspective has influenced other projects around the world. In Guatemala, the Pacunam LiDAR Initiative, involving the Polytechnic University of Valencia in Spain and Tulane University in the US, identified thousands of Maya structures concealed beneath the dense jungle canopy, including elevated roadways and agricultural terraces.

In Cambodia, a combination of satellite imagery, radar, and large-scale LiDAR surveys confirmed the existence of an extensive urban network beneath the forests surrounding Angkor Wat. In the United Kingdom, the Stonehenge Hidden Landscapes project used ground-penetrating radar and remote sensing to detect prehistoric monuments buried around the megalithic complex.

In each of these cases, archaeology has moved beyond the study of isolated monuments to examine entire landscapes and the relationships between settlements, infrastructure, and the natural environment.

With this project, which we completed in December 2023, we overcame a particularly demanding challenge—not only because of the hospital’s size, but also because of the tight construction schedule of just 26 months. Throughout the construction process, we had to navigate extraordinary circumstances such as the COVID-19 pandemic, a transportation strike, and the war in Ukraine.

Together with two of the key figures involved—Pedro Gallego, Director of Hospital Construction, and Pedro Luis Rodríguez, Site Manager—we look back on the challenges, the teamwork, and the dedication of our professionals who made this major project possible.

The 12 de Octubre Hospital is the sixth flagship project in our series on Sacyr’s 40th anniversary, which we began in January with the Los Vilos-La Serena highway in Chile.

We invite you to discover it in this new video.