What Seismic Risk Reveals About Cultural Heritage: Inside the Mosque-Cathedral of Córdoba

What Seismic Risk Reveals About Cultural Heritage: Inside the Mosque-Cathedral of Córdoba by Isabel Cuerda

Bell Tower of the Mosque-Cathedral of Córdoba: a vertical palimpsest. 

There are places where history breathes in stone and wood. Where light falls in ways that seem rehearsed across centuries, tracing the memory of artisans, rulers, travelers, and ordinary people who once stepped across the same worn pavements. The Mosque-Cathedral of Córdoba is one of those places – an architecture of superimposed stories, a living palimpsest. Its arcades, alternating red and white, seem to extend infinitely like a mathematical rhythm. Its columns – Roman, Visigothic, Hispano-Muslim – speak of reuse long before sustainability became a contemporary obsession. Its spaces form a kind of memory-scape: a building that does not simply house history but is history.

When we talk about protecting such a monument, we’re not only referring to the preservation of a structure. We’re talking about safeguarding an identity. The Mosque-Cathedral is not merely one of the most ambitious religious buildings ever constructed in Europe; it is a symbolic intersection of cultures, beliefs, and worldviews. It encapsulates the story of al-Andalus, Christian Renaissance interventions, and the ability of architecture to adapt without losing its soul.

Yet even monumental architectures – those we assume to be eternal – are vulnerable. Today, the pressures on heritage are not simply the age of the stones, but the shifting world around them: environmental change, social demands, tourism, and yes, the silent but potent force of earthquakes.

This fragile balance between history and nature is where the SAFE-HERITAGE project finds its purpose.

For me, this research path is closely connected to my experience as a former student in Yacademy’s Architecture for Heritage program. The discussions in Bologna and Venice around risk, reuse and the future of historic sites provided a framework that I now bring back to Córdoba.

Frontal view of the Mosque-Cathedral of Córdoba.

A Heritage Landscape at Risk

Cultural heritage sites are often imagined as immovable, timeless objects, but they are far from passive. They live outdoors, under the sun, rain, wind – and in some regions, under the persistent possibility of seismic activity. Southern Spain is one of these regions. Although not as notorious as Italy, Greece, or Turkey, Andalusia experiences a seismicity shaped by the meeting of the Eurasian and African tectonic plates. The earthquakes may be moderate, but for ancient masonry buildings – structures whose logic predates modern engineering – this can be enough to cause irreversible damage.

Imagine the hypostyle hall of the Mosque-Cathedral during an earthquake: hundreds of columns and double arches working together like a forest of stone, each one transmitting forces in its own particular way. No two columns are identical. Materials vary from marble to granite to limestone; many pieces are repurposed from older temples. The arches, with their alternating bands of stone and brick, create not only beauty but a structural system unique in the history of architecture.

This heterogeneity is part of the building’s charm – but also part of its vulnerability. The layered history that makes the Mosque-Cathedral extraordinary is the same complexity that makes its seismic behavior difficult to predict.

Interior view of the arcades of the Mosque-Cathedral of Córdoba.

Why Preservation Today Means More Than Restoration

In heritage conservation, the question is no longer simply how do we restore a damaged monument? The more urgent question is: how do we prevent damage from happening in the first place?

In a century that will be defined by climate change, shifting populations, and environmental uncertainties, the idea of preservation must evolve. We must move from reactive to proactive strategies, from isolated interventions to holistic understanding. Heritage is not only a built object; it is an ecosystem – of materials, stories, rituals, and community identity.

The SAFE-HERITAGE project responds to this change of paradigm. Its ambition is both technical and cultural:

• to protect heritage not by altering it, but by understanding it,
• to anticipate risks rather than wait for emergencies,
• to ensure that decisions made today respect the authenticity inherited from the past.

This means developing methodologies that blend architecture, engineering, digital technology, and historical knowledge. It means learning to “listen” to buildings – observing their free vibrations, tracking subtle shifts, understanding how centuries-old materials behave under stress. The goal is not to impose modern solutions on ancient structures but to uncover the structural logic they already possess.

View from the roof of the arcades of the Mosque-Cathedral performing free ambient vibration tests.

Córdoba as a Living Laboratory

The Mosque-Cathedral of Córdoba offers a unique opportunity for this new way of thinking. Each of its four major construction phases introduced new rhythms, new systems of space and structure. From the early mosque of Abd al-Rahman I to the later Al Mansur extension and the Christian cathedral nave inserted in the 16th century, the building represents a continuous architectural negotiation between eras.

In this monumental labyrinth, the SAFE-HERITAGE team began by focusing on the oldest sector: the Abd al-Rahman I hall. Here, more than anywhere else in the complex, the building embodies the spirit of reuse – shafts taken from Roman villas, capitals carved and re-carved, stones bearing the marks of previous lives. This area also contains the archetype of Córdoba’s double-arched system, the element that later influenced both Western and Eastern architectural traditions.

Studying this sector is like examining the DNA of the monument. Understanding its behavior under environmental and seismic forces allows researchers to build a vision for the entire building.

Chronological evolution of the ground plan of the Mosque-Cathedral of Córdoba (based on Almagro Gorbea A. Mezquita de Córdoba. Planimetrías de Arquitecturas de Al-Ándalus).

Rising above this horizontal forest of columns, the Bell Tower is an important landmark on Cordoba’s skyline and a key case study within SAFE_HERITAGE. It encloses within its masonry the original Caliphal Minaret of Abd al-Rahman III, preserving it as a hidden core inside the later Christian structure. This vertical palimpsest encapsulates the convergence of Islamic and Christian cultures. Because of its height, mass and stratigraphic construction, the Bell Tower is a clear example of the seismic vulnerability of heritage towers – and a reminder of why they must be carefully safeguarded.

General view of the Bell Tower of the Mosque-Cathedral of Córdoba.

Architecture Meets Technology: A New Way of Reading Old Buildings

To preserve heritage today, architects and researchers must learn to work with buildings as dynamic organisms. SAFE-HERITAGE does this through a combination of traditional knowledge and advanced tools.

Listening to the Building: Non-Destructive Testing

Because historic monuments are fragile, researchers rely on non-invasive methods – subtle vibrations, sonic waves, scans that detect internal voids or irregularities. In the Mosque-Cathedral, they reveal how the columns behave as a collective, how the arches contribute stiffness, and how centuries of transformations have shaped the current equilibrium.

Digital Twins for Ancient Structures

The project creates detailed 3D digital models – a kind of architectural “twin” – that reproduce the building’s geometry, materials, and mechanical behavior. But these models are not abstractions; they are calibrated using real data gathered on site. They allow experts to simulate scenarios that we hope will never occur: the shockwaves of hypothetical earthquakes, the progression of damage, the paths of forces within the masonry.

This is not to make the building earthquake-proof – no ancient structure can be made invulnerable – but to learn where it is strongest, where it is fragile, and how to act wisely if conservation interventions are ever needed.

A Cultural Tool as Much as a Technical One

The most powerful contribution of this approach is not the digital model itself but the dialogue it enables. Conservators, architects, historians, and structural experts can now speak a shared language, grounded in both technology and cultural meaning. Decisions can be made with a level of clarity and empathy that respects the building’s identity.

The Broader Impact: Protecting Memory

SAFE-HERITAGE is ultimately about resilience – not only of structures but of societies. When a heritage building is damaged or lost, what disappears is not only stone and mortar but a part of collective identity. Places like the Mosque-Cathedral carry emotional, spiritual, and symbolic value that cannot be quantified.

Preserving them strengthens the resilience of communities, offering continuity in a rapidly changing world. It connects the past with the future, ensuring that the architectural stories we inherited remain accessible for those who will follow.

In 2026, many of these themes will be part of the conversation at the 11th European Workshop on Irregular and Complex Structures (11EWICS), where cultural heritage and seismic understanding meet. The Mosque-Cathedral stands as a perfect embodiment of complexity – geometric, material, symbolic – and therefore as an ideal reference for the future of seismic-aware heritage preservation.

A Monument That Teaches Us How to Care

Walking through the Mosque-Cathedral, one feels that the building teaches something essential about coexistence: between cultures, between time periods, between architectural languages. Today, we must learn to extend that coexistence to the relationship between the past and the risks of the future.

Heritage preservation can no longer be an act of nostalgia; it must be an act of foresight. Projects like SAFE-HERITAGE invite us to rethink how we care for ancient buildings – not as museum pieces, but as active players in the life of contemporary cities.

The forest of columns in Córdoba has stood for over twelve centuries. With the right tools, understanding, and respect, it may very well stand for many more. Safeguarding this monument means safeguarding a chapter of world heritage that belongs to all of us – a reminder that architecture, when cared for, becomes a resilient form of memory.