1Introduction

Professionals involved in the protection of heritage buildings need to reflect on how the change of use affects sustainability. The case of the Spanish Cathedrals is a very clear example, but this dynamic also affects to architectural heritage all over the world. This is a step to encourage  the  development of a knowledge to highlights the need to investigate and consider adaptive reuse in the context of maintain  architectural quality in buildings of exceptional cultural value (vg, the current situation of convent of Van der Laan in Belgium, the former Embassy of the USA of Breuer in The Hague, etc.)

Cathedrals have a special significance; the current pressures they are facing must be solved in the field of SDG, considering “the fact of the role of culture, through cultural heritage and creativity, as an enabler of sustainable development across the Sustainable Development Goals” , according to (UNESCO 2019) [i], and  “the protection of exceptional heritage properties cherished by people all over the world – such as great natural sceneries and landmark monuments - can be considered as an intrinsic contribution to human wellbeing”

In the context of studying the reuse of religious buildings, Cathedrals offer a specific particularity. These buildings maintain their original use but are being gradually modified in order to adapt to new challenges. However, since these circumstances are transforming their purpose progressively and inadvertently, they are undergoing, de facto, a silent change of use.

From their original purpose as sacred places they present an evolution to become museums, places of cultural events and objects of touristic consumption, purposes for which they were not built. The evolution of the management of this heritage has a dynamic that causes an undeclared, and perhaps not conscious, reuse that deserves to be analyzed.

The study of how this dynamic evolves is particularly important for its exemplariness. There is not a single town in Spain without Catholic religious heritage of churches, parishes, hermitages, convents, monasteries, etc. [1] and most of them have difficulty keeping up maintenance.

2Background

A Cathedral (as definition) is the temple in which the bishop has his seat or “cátedra”. The Catholic Church in Spain is made up of 14 ecclesiastical provinces, divided into 70 dioceses, led by a bishop^[ii]. These dioceses are distributed across 50 administrative provinces. On the other hand, the Plan Nacional de Catedrales (Rodríguez Blanco, M. 2003) ^[iii] (National Plan of Cathedrals), the specific instrument of the State to manage them, includes 90 cataloged buildings (between cathedrals, con-cathedrals and basilicas)

This disparity of figures already indicates the particular administrative situation of these buildings between the State and the Catholic Church. According to the Catholic Church, ^[iv] the cathedrals:

“[...] are artistic creations for divine service, which express faith and are an extraordinary instrument to evangelize those who contemplate them. It has a liturgical, evangelizing and pastoral purpose, while being open to the study and contemplation of society.”

While, for the State administration^[v],

“Cathedrals are complex monuments resulting from a collective and prolonged effort over time. In addition to their religious content, they also possess the social and symbolic values ​​that create our cities, becoming their spatial reference, conditioning their urban planning and becoming the physical expression of their identity. Within the integral concept that today defines what is cultural heritage, the cathedral complex manifests all their historical background and are the best evidence of the great historical lines of artistic and evolution of thought. In that sense, they are the leading role of the urban landscape whose evolution continues until today. Furthermore, they are historical monuments but still alive. Their current image, both in their architecture and art they contain, is the result of successive episodes of superposition, extension and reform.”

And for a writer (Llamazares, 2018, a) ^[vi]

“Cathedrals are the “black boxes” of the cities; they summarize their gist, contextualize them.”

They are secular buildings; their life cycle is measured in centuries and even millennia, and in this unit of measure they must be analyzed and studied. The history of these buildings dates back to the history of religion in Spain. Cathedrals as a whole concentrate all known artistic styles from evangelization in the first century to the twentieth century, not only in architecture, but in many other artistic manifestations such as sculpture, painting, ironwork, carpentry, tapestry, gold and silversmithing,  textiles, furniture, codices, books, musical instruments, glassware, plasterwork, etc. [Fig. 1]

3Challenges in the current context

The current pressures suffered by the cathedrals can be synthesized, at least, in the following:

3.1Socio-cultural and religious changes

Since 1975, sociological changes show a continuous and notable decrease in Catholic following. However, at present times, 69.2% of Spaniards still declare themselves Catholic (one third of which are observant), 2.2% follow of other religions and 28.6% consider themselves atheists, agnostic or indifferent to religion^[vii]. The increase in urban population in Spain contrasts a decline in rural population, where a large portion of religious heritage is located. As an example, the region of Castilla y León, with a surface area of ​​94,226 km2 (twice the size of The Netherlands), currently has 2.5 million inhabitants, (one fifth of The Netherlands), and has 2,294 monuments catalogued BIC^[viii], (Bienes de Interés Cultural, Goods of Cultural Interest), of which 12 are cathedrals.

The clergy has also declined markedly (Orlandis, J. 2003). ^[ix], especially in monasteries. The maintenance of the religious uses, including in cathedrals, is challenging in these circumstances.

3.2The maintenance of artistic works

Cathedrals have accumulated a great quantity and variety of artistic works throughout centuries, through donations from churchgoers or the ecclesiastic hierarchy itself: altarpieces, paintings, sculptures, goldsmithing, forge, stalls, furniture, codices, bibliography, ethnography, musical instruments, textiles, tapestries, ecclesiastical clothing, etc. [Fig. 2]

The objective of these artistic pieces is closely related to the Eucharistic use and the authenticity of the building. These buildings are one of the few instances in which the works of art are exhibited at the same place for which they were made, and the circumstances of their contemplation are similar the original ones; this contrasts the ubiquitous practice of displaying artworks in museums and galleries, far from their original context.

Their maintenance requires a microclimate and strict environmental conditions in temperature, humidity, air quality and movement, but also safety against accidents, fire, theft and vandalism. Furthermore, each artistic piece requires specific environmental conditions. Nowadays, these conditions must be maintained in spite of external forces (changes in weather, noise pollution, traffic) and the comfort needs of users, especially in temperature and humidity, which are not always coincidental. Any damage could be irreversible. Therefore, preventive conservation is required. (Herráez, J. A. 2009). ^[x]

3.3Tourism management

In recent years, the pressure of tourism has increased enormously, especially affecting well-known buildings as universal heritage, both because of the so-called effect of a UNESCO- site and the economic opportunities of the tourism industry. The Basilica of Zaragoza, Santiago de Compostela, the Sagrada Familia in Barcelona and the Cathedral of Cordoba each receive 3 to 5 million annual visitors. The Cabildos (cathedral chapter, priests responsible) are overwhelmed with the difficulty of managing and maintaining these buildings and the expenses that it entails. The apostolic mission and the cultural aspects of the buildings are reduced and annulled confronted by the industrial and recreational facet of tourism, and whose dynamics far exceed the provisions of the Plan Nacional de Catedrales.

The Cathedral, an urban, social and religious center in other times, is now an obvious resource of tourist potential, economic wealth and production of jobs. In the current secular time, is this compatible with their religious use? The UNWT (United Nations World Tourism Organisation) ^[xi] suggests “sustainable tourism”, defined as

"Tourism that takes full account of its current and future economic, social and environmental impacts, addressing the needs of visitors, the industry, the environment and host communities.”.

But does anyone know exactly how this is managed in a Cathedral? Isn't it an oxymoron?

3.4The technological update

The use of very elementary technologies (electrical system, primary heating systems) introduced changes in the internal image of cathedrals. After that, the Second Vatican Council (1962-65), an important religious milestone, introduced significant conceptual changes in the rites, the participation of churchgoers and the spatial distribution of churches, to which the cathedrals also adapted (other centrality, changes in the altar and in the baptistery, etc.) Gradually, pulpits were abandoned, or disappeared (these were often valuable artistic pieces, such as that of the Cathedral of Valladolid) or were replaced by electrical cables and conduits, speakers and microphones, in an improvised way but accepted by the public.

One of the particularities of many Spanish cathedrals are the choirs and their sillerías (seats), placed in the central nave according to their function (Navascués Palacio, P. 2001) [xii]. Due to them, and despite the large dimensions of the cathedrals, the participatory space (as we consider it in present times) is relatively small. Electronic screens have been placed to follow the acts in the side aisles or spaces without visibility towards the presbytery. Gradually, elements of monitoring, security, control (input turnstiles), fire protection (sensors, fire extinguishers), signals, codes for audio guides and other devices have been necessarily appearing on the sacred space, but often haphazardly and designed in disarray with the quality of the building. Nobody has protested about those devices since even being strange elements in a church, we find ourselves familiar with them.

However, visual impact is important. These small practical interventions, apparently innocuous, carried out urgently and needfully are introducing changes in the image, perception and use of the building imperceptibly and cumulatively. Any operation, however small or big, to enlarge the life span of the building requires a project of the complete impact, an impact projection, and specialized, heritage-sensitive technicians and hierarchical criteria on intervention.

3.5New demands.

Accessibility (barrier suppression, sign language, braille, magnetic induction loop, typhlology, etc.), comfort and energy efficiency are criteria that are now required in religious buildings, also in cathedrals.

“Sooner or later, monuments - including those dedicated to worship - are similar in many ways to any new building. This circumstance must be taken advantage from what in the new norms can agree or benefit to the monuments”. (Garcés, M. 2009). ^[xiii]

Indeed, a cathedral is a very special area, in which the building codes required for standard buildings must not be assumed according to conventional criteria. Their conditioning, especially heating, is perhaps the one that produces the greatest impact on the buildings (many cathedrals are located in the northern half of the Iberian Peninsula, where the winter is very severe). The introduction of heating systems, optimized for new construction, presents great difficulties in historical buildings. The quality of the materials, including the floor (an element of the same architectural importance as any other structural element) can suffer great damage due to the inclusion of inadequate heating systems.

Damage can also be irreversible in works of art when the climate conditions inside the cathedral, naturally maintained for centuries, are modified. The introduction of any conditioning system must be justified. Any change must be applied from the understanding and respect for the individual character of the building, and its justification and need must be clearly defined. ^[xiv],

The life span of a cathedral is measured in centuries or millennia, and scenarios must be established in these terms. We must guarantee the reversibility of any action (Camuffo, D. 2006). ^[xv], (Spolnik, Z., Worobiec, A., & all. 2007). ^[xvi] . Tectonics lasts centuries; additions last for decades. That was the purpose of the “Estudio sobre acondicionamiento térmico para la Catedral de Burgos” (giSCI-UPM, 2013). ^[xvii], (Study on thermal conditioning for the Cathedral of Burgos) , replacing the previous idea of ​​introducing floor heating, aggressive for the historic floor,  with a harmless system for the cathedral's tectonics and one with a rigorous control of microclimatic variations. (González Díaz, M. J. 2019). ^[xviii]. [Fig.3]

The requirement of energy efficiency and the use of renewable energy in the management of the conditioning of religious buildings is other important current requirement that hardly fits into this scenario. Heating is not an objective in itself, but to improve the comfort conditions of the users. In this case, the strategy of Pretelli, M., Fabbri, K., & Signorelli, L. 2015) ^[xix] and (Fabbri and Pretelli 2014)^[xx] is the most appropriate. Therefore, the application on heritage buildings of tools prepared to ensure energy efficiencies in standard buildings is limited. ^[xxi]

4Management and property.

Compared to other countries, cathedral management is a particular case in Spain.  The competency between the State and the Church (Holy See) stems from the Acuerdos (Agreements), especially that of 1979[2], which have range of state agreement. The works on the heritage maintenance are in accordance with the Ley del Patrimonio Histórico Español (Spanish Historical Heritage Law), autonomous legislation, and national and international recommendations.  Public authorities support the Chapters in their task of preserving the monuments. In summary, it is a joint action between the Autonomous Communities, the Central Administration, and the Church itself.

The cited Plan Nacional de Catedrales is a state plan that manages and determines the risks factors related to stability and tightness, seismic and catastrophic hazards, and the effects of atmospheric pollution of the environment (urban, industrial, etc.). It also provides for the incidence of specific meteorology (microclimate) and the effects of demographic variations, the intensity of touristic use and the possible lack of maintenance and the incidence of theft, vandalism, etc.

This plan was a collaboration agreement from 1997, between the Ministry of Education and Culture and the Catholic Church. After 20 years, state self-criticism recognizes an insufficient economic investment, and many other cases in which only one of the parties has participated[xxii]. The fact of the matter is that the circumstances and the evolution of events are much faster than the forecasts of the document, and any management to different bands, with different interests, can be a source of diverse opinions and even controversies.

5Basis for discussion: Authenticity vs. Adaptation?

The challenges mentioned describe a pressing scenario. Each of the cathedrals faces these challenges in one way or another. The result of these difficulties is solved day by day, making them compatible with their religious use. Small update actions are apparently harmless. However, nothing is harmless. Lighting is essential today, but it is not the same to illuminate for the religious service as for the tourist function. Heating them up; it’s really necessary? Accessibility: is it truly necessary to comply in the same way as in a conventional building? Does the furniture not influence the use of space? Do all these elements not affect the appreciation of the interior space of the architecture? Control turnstiles and armed security guards: are they compatible with a Church?

Tourism is considered harmless or even beneficial, as it produces economic profitability. Attempts have been made to solve the compatibility (or incompatibility) between tourism and religious services through separate accesses between tourists and parishioners. For the daily religious rites small chapels, free access exclusively for prayer is isolated. Main ship spaces, or sometimes entire cathedrals, are destined only for special events of the Church, (Easter, the Saint of the city, or others)   in which they are open to all public. Commonly, the rest of the time they are open for tourists under an entrance fee (currently, ranging from 2 to 25 euros, reduced for some groups or neighbors).

This is the case in the cathedrals with the greatest tourist attraction (Seville, Burgos, Segovia, Salamanca, Toledo, etc.). Other, such as Valladolid or Barcelona (Cathedral of Santa Creu and Santa Eulàlia,  not to be confused with the Basilica of the Sagrada Familia) are open at their usual time for all those who wish freely visit it. Less than twenty cathedrals maintain the free entrance for anyone who wants to visit them, either to pray or with a cultural objective. A notable exception is the Cathedral of Santiago. Despite its 3 million annual visitors, it is open for free. The dean "does not even consider the option of collect” The archbishop of Santiago says that the Cathedral is the "pilgrimage Church of the world", so "it has to be open to pilgrims." ^[xxiii]  The other four less known Galician cathedrals (Tui, Ourense, Mondoñedo and Lugo), require a fee to visit their interior. [Fig.4]

Services such as guides, audio guides or guided visits are considered lawful to charge. Cathedrals frequently have many other annexed religious dependences such as cloisters, sacristies, diocesan museums and cathedral treasures, where art pieces are exhibited as a museum experience, under payment. Other annexes are the Observatory of Cathedral, stairs to the tower, etc. It is obvious that these revenues represent an important and constant economic income, necessary to aid maintenance.  The small churches or hermitages, spread over the vast territory, have begun to follow this same system of demanding an entrance fee, however small, for the maintenance of the building.

Certainly the difficulty of maintaining heritage, and especially after the fire of Notre Dame de Paris, has become obvious. Cathedrals stand at a great cost. According to (Delclaux, P. 2019) ^[xxiv]., Director of the secretariat of the Episcopal Conference for Cultural Heritage, "cathedrals remain thanks to becoming museums" But that is controversial. In Castilla y León, 3% of the buildings listed as cultural monuments have been reused, usually monasteries desacralized and repurposed as hotels (Nóra Kóródy, A., & Vukoszávlyev, Z. 2015)^[xxv], or simply left in ruins. In the context of religious architecture, cathedrals are an exception, since they are standing and in use.

6A specific methodology

Facing such a wealth of heritage, experts (Garcés, 2009)[xxvi] advice preventive conservation against rehabilitation or restoration, and especially against the urgent restoration strategy. New research[xxvii] has been done and BIM technical models have been created to collect more information on heritage buildings[xxviii], but these were limited to the study of the energy issues and are oriented to the application of existing commercial devices, which are unable to solve the particular problems of these unique buildings. Under the argument of energy efficiency, tools that ignore the special configuration and secular structure of these buildings are applied. There are no universal answers to these specific problems, and therefore the management of cultural heritage must be focused on the unique values ​​that each cultural good possesses. Decisions must be made considering long-term consequences and making the fewest possible alterations. These criteria should be valid in technical matters and in symbolic and cultural ones too. The authentic and true revealing dimension of the objective of the building must be preserved.

On one hand, cathedrals remain standing and, in general, in good condition, despite the difficulties. On the other hand, it is evident that the process of change of use that inadvertently is transforming churches (sacred spaces, according to their owners) into museums at best, or objects of touristic consumption, at worst.

What methodology to use for the complete maintenance of these buildings? How to maintain its authenticity? All maintenance or updating of the building requires a very clear hierarchy of values, in whose pyramid the highest point must be an ethical concern. Any intervention in a cathedral must abide by that order of values ​​with subordination.

7Still a sacred building?

The value of heritage radiates from its complete inheritance and its complexity. A Cathedral it is probably today the only place where works of art remain in their authentic and original environment (not in a museum). The altarpieces, the paintings, the tombs, the sarcophagus were made for that place and that religious objective. They were received from the donors or by the religious authorities themselves for that purpose, and they remain there are after five, ten or fifteen centuries.  The liturgical use, reformed in the last century, and the faith that produced it, also exists.  The structure, the content and the use must be respected and maintained in its own state. Otherwise the space loses its significance and the architecture results empty. 

Cathedrals are also part of an intangible heritage, which, from a secular or even atheist point of view, can be assimilating the religious beliefs. The purpose of the building, the one for which it was conceived, is the worship of God and the evangelization, as described by its owners. This use is incomprehensible when it is placed in a no man's land between a part-time consecrated building and a museum. The Church, as a collective, in its twenty centuries of history, has been open to all, according to its own beliefs. [Fig.5]. The separation between those who come to visit the building (under fee) and those who come to pray is therefore incongruous. The building has lost its authenticity, what is its own, this that it has been along millennia, to transform into the 21st century.

Another topic for debate is whether a building stripped of its original purpose maintains its heritage value. A desacralized church, converted into a hostel or restaurant for private initiative (common case) becomes a shell whose architectural and stylistic value remains remarkable, however its cultural, symbolic and representative value for the community has diminished significantly. The symbolic value of the cathedrals for the city, for the people and their culture is maximum, hardly surmountable. Once this symbolic charge is diminished (or disappears), does it maintain its own value? Let's remember that the religious faith for which it was built still exists, but is being gradually expelled from the building.

This feeling is described by the writer Julio (Llamazares, 2018 b) [xxix]:

The temples ... allow to unravel the soul of the cities that created them. ... They talk about the withdrawal of that soul from the cathedrals when the churches charge entrance and exchange the parishioners for tourists ... when they charge to enter, the cathedrals  lose their soul and become containers of stone and beauty, but without a beat of life. Cathedrals have been closed to the life of the city. The neighbors no longer consider them theirs because, when they charge you for entering a site, they no longer feel it as something of their own. They have killed life in cathedrals, not only religious life, but that of contemplation, of enjoyment. I used to visit the cathedral every time I went to León. Not now, not for not paying the euros they cost, but because inside you will only find an empty shell, full of people with audio guides, wandering around like automatons.

Other parishioners address the debate on an ethical-moral dimension, which they describe directly:  (Latorre, L. 2019). [xxx]

"Catholics who visit the Cathedral to attend mass or pray think this is now Disneyland."

Architecture is an idea, not a mere construction, and the cathedral concentrates the maximum meaning. Its sustainability and at the same time the safeguarding of its authenticity becomes extremely difficult. How to find the right balance between updating and maintaining the authenticity of the building?

8Conclusion

The use of a Cathedral as a museum is a controversial matter:  Church-authorities and parishioners may have different views.

The Church in its capacity as owner on one hand may consider touristic use of its Cathedral as important, and even necessary to finance maintenance. The parishioners and the religiously inclined on the other hand could disagree because they may consider turning a Cathedral into a museum is inappropriate and in contradiction to the authenticity of the building as a sacred place. The respect of its original purpose should be paramount in any decision. The question is whether a Cathedral can be at the same time a museum.

A vicious circle looms: the more the owner is intent on preservation of the monument, the more this may be at the expense of its authenticity. Sustainability of a building, Cathedral or otherwise, should include respect for the purpose for which it was built originally.