MARÍA GÓMEZ BRAVO | Tungsteno

At eleven o’clock on the morning of February 20, 2026, a crane hoisted into place the final arm of the cross that crowns the Tower of Jesus Christ at the Basilica of the Sagrada Família in Barcelona. With that, a major chapter in the basilica’s 144-year construction history reached its culmination. With the installation of the steel, glass, and ceramic structure, the Roman Catholic basilica attained the 172.5-meter height envisioned by Antoni Gaudí and became the tallest church in the world. The solemn blessing and inauguration ceremony, presided over by Pope Leo XIV on June 10 as part of the events commemorating the centennial of the architect’s death, underscored the tower’s symbolic significance.

Yet the completion of the tower represents more than just an architectural record. It is one of the most complex exercises in heritage continuity in contemporary architecture: completing a project conceived in the 19th century using tools, materials, and construction systems that its creator could never have imagined.

The basilica’s changing silhouette also marks the beginning of a new chapter for a building that continues to face questions that engineering alone cannot answer.

The installation of the final arm of the cross that crowns the Tower of Jesus Christ marked the culmination of a 144-year construction process. Credit: Fundació Junta Constructora del Temple Expiatori de la Sagrada Família / Pep Daudé

A Mountain as a Limit

When Gaudí took over the project in 1883, he transformed a conventional Neo-Gothic church into a complex architectural organism in which every element responded to a geometric, natural, and symbolic order. The Tower of Jesus Christ was not simply the tallest of the 18 planned towers—it was the axis around which all the others were arranged.

The architect did not design a building composed of independent parts, but rather a system in which form arises from complex mathematical and structural relationships. Surrounded by the towers of the Evangelists and that of the Virgin Mary, the central position of the Tower of Jesus reflects a spatial and theological hierarchy in which height expresses the order of the whole. Its location also strengthens the building’s visual relationship with two defining features of the Barcelona landscape: Montjuïc and the Mediterranean.

The Tower of Jesus Christ acts as a connector between Montjuïc and the Mediterranean Sea. Credit: Fundació Junta Constructora del Temple Expiatori de la Sagrada Família / Pep Daudé

This decision reveals much about Gaudí’s conception of architecture. The Catalan architect specified that the structure should reach 172.5 meters in height, deliberately placing the tower just below the 173-meter summit of Montjuïc in order to integrate the basilica with the city’s natural skyline rather than compete with it.

Between Legacy and Interpretation

Gaudí conceived the Sagrada Família as an intergenerational project. He understood that the technical complexity of his vision, combined with its reliance on private donations, made it impossible for him to see it completed. As architect Joan Bergós, one of his closest collaborators, later recalled, Gaudí often said: “What I cannot do, others will continue.”

When he died after being struck by a tram in Barcelona in June 1926, the Tower of Jesus Christ remained more idea than reality. Gaudí had defined its role within the overall composition, its general proportions, and many of its geometric principles, but he never lived to see its construction begin. The destruction of many of the models and documents stored in the Sagrada Família workshop during the Spanish Civil War dealt the project a further blow. The surviving legacy had to be pieced together and interpreted to meet the challenge of completing the building’s unbuilt sections, including the great central tower.

The Tower of Jesus Christ has become one of the finest examples of collaboration between heritage and innovation. Credit: Basilica of the Sagrada Familia.

When construction began, many of the shapes envisioned by Gaudí were simply impossible to build. A century later, computers made it possible to visualize much of that geometry. Australian architect and researcher Mark Burry, one of the foremost academic authorities on the basilica, has played a key role in this process. His work has helped translate many of Gaudí’s designs into the digital realm using advanced modeling techniques and parametric design tools.

The construction of the Tower of Jesus Christ demonstrates the extent to which digital tools have transformed the way we preserve and restore historic heritage. Many of its components were manufactured off-site and later assembled using industrialized construction methods. Among the innovations employed, the so-called “post-tensioned stone” stands out, a system that combines stone and steel to increase structural strength without altering the building’s exterior appearance.

The crowning element of the tower—a four-armed cross standing over 15 meters tall—is itself the product of this convergence between Gaudí’s vision and contemporary engineering. The challenge was not merely to place a religious symbol atop the tower. Engineers had to design an element capable of withstanding powerful winds, temperature fluctuations, solar radiation, and decades of exposure to the elements.

The cross that crowns the Sagrada Família’s newest tower is made of steel, glass, and ceramic, engineered to endure the harshest weather conditions. Credit: Basilica of the Sagrada Família

According to information published by the basilica, Gaudí had specified in the Àlbums del Temple that the cross should shine during the day and glow at night. Based on this idea, the resulting solution combines glass, white enameled ceramic, and contemporary structural systems. For Jordi Faulí, the basilica’s architectural director, the incorporation of new technologies has not disrupted the continuity of the project: “If Gaudí were to see the Sagrada Família today, he would recognize it as his own.”

New Challenges

For decades, the unfinished image of the basilica served as both an icon of Barcelona and a metaphor for Gaudí’s nonconformist spirit. Although the Tower of Jesus Christ is now complete on the exterior, the Sagrada Família remains under construction. Work continues on interior spaces and various elements of the complex. Yet the greatest challenge still ahead has a name: the Glory Façade.

Its construction raises a question that extends beyond architecture itself: how do you complete a historic work when the city for which it was designed no longer exists? Conceived by Gaudí as the basilica’s main entrance, this façade was intended to be preceded by a monumental staircase opening onto Mallorca Street, according to the original sketches. Such an intervention would alter the current urban fabric and affect residential buildings that have stood there for decades.

Gaudí envisioned the Glory Façade as the main entrance to the basilica, which has significant implications for the urban environment surrounding the Sagrada Família. Credit: LLUIS GENE / AFP via Getty Images.

The dilemma now facing public authorities and those responsible for the basilica is no longer purely technical. On the one hand, there is the historical question: international organizations such as ICOMOS and UNESCO recognize only the Crypt and the Nativity Façade as part of the Works of Antoni Gaudí, since these are the areas that retain direct material authenticity from the architect’s lifetime. On the other hand, there is the social impact on a city under intense pressure from tourism and urban development. The Sagrada Família, which receives nearly 4.9 million visitors annually and operates with self-financed revenues that exceeded €134.5 million in 2025, functions as a major economic and urban infrastructure.

The cross that now crowns the Tower of Jesus Christ marks the end of one of the most complex chapters in the history of the Sagrada Família. But it also signals the beginning of another. Engineering has succeeded in reaching the height envisioned by Gaudí. The challenge now is to complete his vision in a Barcelona that has changed as profoundly as the basilica itself.

Tungsten is a journalistic laboratory that explores the essence of innovation.

Sacyr Maintenance has started deploying a robotic quadruped to inspect the extensive, kilometer-long galleries deep inside dams. These critical hydraulic structures often have thick concrete walls, which severely restrict external connectivity and make traditional inspections challenging. An autonomous robot, therefore, offers an ideal solution. This advanced machine assists professionals with routine checks and can identify potential hazards like dangerous gases or excessive moisture before they become critical.

The Duero Hydrographic Confederation originally proposed this autonomous robotic inspection project. They specifically suggested deploying the quadruped at the Pontón Alto dam, situated between Segovia and La Granja.

This system significantly enhances both inspector health and safety, alongside boosting operational efficiency by allowing for more frequent inspections.
Jose Luis Barragán, COEX Dam Manager for Zone F of the Duero Hydrographic Confederation (where Sacyr Maintenance operates), explains: "The galleries the robot explores contain vital components such as water supply valves and sluice gates. While existing sensors monitor parameters like pressure, flow, and displacement, our goal is for the robot to photograph specific, predetermined points."

"These different gallery levels are connected by stairways, enabling UGV (Unmanned Ground Vehicle) robots to move freely between them for thorough inspections. This represents our first time incorporating such advanced technology into dam conservation," Barragán adds.
 

The challenge is in the location 

The immediate challenge lies in implementing an effective robot localization system, particularly since GPS signals are unreliable deep inside the dam. To overcome this, Sacyr Maintenance is exploring solutions like creating a detailed 3D map or developing a digital twin of the galleries.

"In the future, the robot could be trained to do more than just capture images. It could also extract and analyze data, proactively preventing issues like cracks, moisture ingress, and excessive seepage," the expert suggests.

Initial navigation tests have already been successfully conducted, with ongoing development planned for the coming months.

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.