The rehabilitation of the Daoíz y Velarde Cultural Centre in Madrid, Spain, presents a good precedent in the potential and challenges of adapting historical buildings for modern use. The Daoiz and Velarde barracks, constructed in the 1880s on a 23,000 square meter land area known as "Los Docks," have two distinct barracks for infantry and artillery. It was designed as a complex of military factories with direct access to Atocha station and was capable of housing 3,500 soldiers and 500 horses, and the carriages of a mounted artillery regiment (Ugc, 2024-07-20).

The rehabilitation plan was designed by Rafael de La-Hoz Arquitectos and was completed in 2013. The project transformed 19th-century military barracks into a lively cultural hub using innovative strategies to preserve architectural heritage while meeting modern needs (Valenzuela, 2024). The primary challenge lies in balancing the preservation of the building's historical features and fulfilling the requirements of contemporary cultural functions. This was achieved by preserving the original brick facade and special sawtooth metal roof, while creating an interior to create flexible, multi-purpose spaces for different cultural activities (Valenzuela, 2024). The architects used a strategy of "selective intervention," preserving the external shell while emptying the interior to form open, adaptable spaces (Figure 1). A new concrete structure has been inserted within the historical envelope, providing modern structural support and integrating advanced sustainable technologies (Mansanrod, 2017).

This method preserved the building's urban personality and historical excellence while implementing a comprehensive functional transformation. The design also addressed sustainability concepts, integrating geothermal energy systems for heating and cooling, thermo-activated concrete structures for climate control, and optimized natural lighting and ventilation (Daoíz Y Velarde Cultural Centre / Rafael De La-Hoz, 2024). These systems enhance a building's energy efficiency and represent a model of how historical structures can be adapted to meet modern environmental standards. The cultural center includes two distinct theater halls, each with its own unique layout. One follows the traditional Italian design, whereas the other adopts a more versatile cruciform configuration that can be adapted to various arrangements. This flexibility allows for a wide range of performance styles and audience settings. The design further enhances flexibility, with open floor plans and movable elements allowing for easy reshaping of spaces to fit different events and functions (Valenzuela, 2024) (Figure 2, Figure 3, Figure 4, and Figure 5). This flexibility establishes the building's long-term viability, as a cultural center can evolve with changing community needs.

Another key aspect of rehabilitation is the enhancement of public spaces. The renovation extended the adjacent plaza into the building, creating a covered public gathering area that served as a transitional space between the urban environment and the cultural center. This strategy enhanced the building's integration with its surroundings and increased its value as a community center. The ground floor included the main entrance and functioned as a common area. It is designed to work as a covered agora or plaza, and is used as a meeting place, information center, and exhibition space. The design allows for an open, fluid, and visual connection with the exterior. The Basement hosts cultural activities and includes an auditorium for conferences and performances. A project's success lies in the balance between preservation and innovation.

By clearly distinguishing between historical elements and modern interventions, the architects created a dialogue between the past and present, allowing visitors to appreciate both the building's heritage and its contemporary function (Valenzuela, 2024). The Daoíz y Velarde Cultural Center rehabilitation is an example of the potential of the adaptive reuse of historical buildings without negatively affecting their architectural significance through solid, innovative design and sustainable technologies that can convert vintage buildings into productive, environmentally responsible spaces that meet modern needs while appreciating historical heritage (Figure 6& Figure 7). The project not only preserved a piece of Madrid's architectural heritage but also established a cultural asset for the community, demonstrating that with the right methodology, historical buildings can be successfully adapted to play important roles in modern urban life (Mansanrod, 2017).

The La Remunta project in Hospitalet de Llobregat, Barcelona, is considered an outstanding case study for the rehabilitation of historical buildings, demonstrating both the threats faced and the opportunities employed in such efforts. This former army barracks, originally devoted to horse breeding, presented a unique opportunity to conserve a piece of local history while modifying it to meet modern urban needs (La remunta - Ravetllat Arquitectura, 2024) (Figure 8). The renovation project focused on four of the six buildings in the old barrack complex: Building 1 (single-story stables, a hall, and dormitories), Buildings 3 and 4 (used for horses), and Building 5 (formerly an infirmary and laboratory). The remaining two structures, an old farmhouse and Building 2, were designated for different developments as nurseries (Figure 9).

The project undertaken by Ravetllat Ribas Arquitectes confronted several significant challenges that are common in historical building rehabilitation. First, the structural deterioration of the buildings needed careful consolidation and rehabilitation work to avoid further degradation (Consolidation of “La Remunta” barrack buildings | Ravetllat Ribas arquitectes | Archello, 2024). This threat was compounded by the unclear future use of the buildings, necessitating an adaptable concept that would conserve the buildings while leaving them adaptable for possible future functions (Consolidation of “La Remunta” barrack buildings | Ravetllat Ribas arquitectes | Archello, 2024) (Figure 10, Figure 11). Moreover, the project had to handle the complex task of integrating these historical buildings into a new urban context as part of the site was being altered into a public park (Villa, 2019-10-24). These challenges echo the broader concerns often confronted in historical building restoration, such as balancing preservation with adaptation, working with unclear future functions, and integrating historical structures into growing urban landscapes (Figure 12,Figure 13).

The strategies employed in the La Remunta Project provide valuable insights into these challenges. The architects conducted selective dismantling and rehabilitation of existing structural buildings, avoiding more invasive interventions, such as reinforcing the supporting structure of the foundations where possible. This method is responsible for conserving the original structural principle of buildings while ensuring their stability for future use. The rehabilitation of the building envelopes was achieved with care for historical integrity, utilizing materials and techniques that matched the original building. Facades were restored using lime mortar and mineral silicate paint, while roofs were rebuilt while conserving current trusses and beams. This attention to detail in material selection and application is necessary to maintain the historical features and credibility of the restored buildings. Mainly, the project demonstrated a sustainable approach to rehabilitation(Consolidation of “La Remunta” barrack buildings | Ravetllat Ribas arquitectes | Archello, 2024) (Figure 14 andFigure 15), respectively. Existing materials were reused where possible, such as recovering tiles from demolition for roof restoration. This strategy not only conserves the historical fabric of the buildings but also adjusts to modern sustainability goals, reducing waste and the need for new materials (Figure 16, Figure 17). The conservation of original elements such as floors, troughs, and animal feeders serves a dual purpose: it maintains the buildings' historical value, allowing future users to connect with the site's past while highlighting the exact features of the restored structures. This method highlights the significance of employing tangible links to the history of a building in rehabilitation projects.

Most notably, the La Remunta project shows the potential for restoring historical buildings to improve urban environments. By successfully integrating rehabilitated barracks with a new public park, the project created a unique space that mixes historical preservation with modern urban needs. This result shows that restored historical buildings can serve as catalysts for urban regeneration, creating spaces that are both historically rich and suited to modern city life. The project was recognized by different organizations, including selections for the Catalunya Construction Awards and the European Award for Architectural Heritage Intervention AADIPA in 2017, which highlights the success of the rehabilitation strategies used (La remunta - Ravetllat Arquitectura, 2024). These awards validate the proposed method and provide a model for future historical building rehabilitation projects.

In conclusion, the La Remunta Project exemplifies the complexities and multifaceted benefits of historical building rehabilitation. It demonstrates how such projects can overcome important challenges through careful planning, innovative design strategies, and commitment to both historical preservation and contemporary relevance. The success of this project in preserving cultural heritage, improving the urban environment, adapting historical buildings for contemporary contexts, and contributing to sustainable urban development serves as a testament to the potential of rehabilitating historical buildings. As cities worldwide grapple with the commitment to conserve their architectural heritage while meeting the needs of urban growth, projects such as La Remunta offer useful lessons and insights for architects, urban planners, and stakeholders.

The documentation and restoration of historical monuments such as the Qishla and Saray of Baghdad face challenges due to erosion, vandalism, and changes in construction over time. The preservation of cultural heritage is important for educating younger generations and preserving the history of society. “In 1831, central rule returned to Baghdad after the fall of the Mamluks. At that time, there was serious consideration of constructing buildings, some with a civilian character, and others with a military character. Among them was the Qishla, which was erected next to the Saray (Palace) as part of a complex housing all the departments related to the military institution in Baghdad.” (Munshed & Ashour, 2024). In 1855, Al-Qishla was built near Al-Serail to be within a large complex; it was constructed to be used as a school under the name of "Al-Mawfakia School,” but later on, the Ottomans turned this building into barracks (Aksulu & Almukhtar, 2021).

Al-Qishla is located near Al-Mutanabi Street in central Baghdad and overlooks the banks of the eastern Tigris River. See Figure 18. The Saray buildings, including the Qishla, were constructed during the rule of Wali Namik Pasha (1851–1852). Namik Pasha erected the Qishla with a single story to house numerous infantrymen during the winter. The upper level was later constructed within Muddhat Pasha's leadership (1869-1872 AD) when the work was finished. “Muddhat Pasha demolished the eastern wall of Baghdad to fund the construction. He also installed a clock in the middle of its courtyard to wake up the soldiers; it was carried on a tall tower (Al-Azzi 1978). In 1917, during the British invasion, the Qishla became an accommodation for British officers and their families; following that, the Qishla served various governmental functions.

In 1991, a decision was made to use the Qishla building as a museum, collecting documents related to the reconstruction efforts after the 1991 Gulf War; therefore, to maintain the quality of the building, it must be occupied with a unified functional program that suits the building and its neighborhood. The Qishla were in good condition and had few problems due to the restoration that took place in 1989. In addition, the Saray gate is structurally sound under good conditions (Aksulu & Almukhtar, 2021). Figure 19 shows the open spaces and the inner eastern façade of Qishla and Saray in Baghdad.

After two decades, it was decided to include the restoration of Al-Qashla in the Baghdad governorate plan, as it had been looted by negligence and waste until some of its historical parts had almost fallen. However, the restoration involved removing the inner partition to create large halls that could be used for exhibitions (Aksulu & Almukhtar, 2021). “Interventions and adaptive reuse of the new expansion for the purpose of reuse included the construction of a new floor above the single-story building with the same ground floor system consisting of a corridor opening onto a series of rooms; it is natural for the corridor on the ground floor to differ from that on the upper floor because they are not synchronized in history’ (Munshed & Ashour, 2024). Figure 20 shows the Ground floor spaces of Qishla, and Figure 21 displays the Eastern wing section. Nonetheless, “Currently, the Qishla and Saray doors are open to tourists and citizens for cultural and recreational purposes” (Munshed & Ashour, 2024).

To elucidate the importance of preserving the historical and heritage remnants of these buildings, which serve as evidence of various eras and play a crucial role in the urban fabric of the city, it is imperative to document them using appropriate scientific methods to ensure their proper maintenance. To sustain these buildings, they must be operated and reused in a way that reflects their value and the urban, political, and military history they embody, thereby preserving them as a living monument.

The Lourcine Barracks, presently a law university that completed its modernization in 2019, is the result of a modern approach to restoring architectural heritage and introducing new methods. This project is located within the old military barracks in the 13th arrondissement of Paris and is organized around a parade ground with its military buildings built in 1875 (ChartierDalix et al., 2023) (See Figure 22).

The Lourcine Barracks have been considerably altered, yet they keep the original design around the historic courtyard and the main north-south orientation. The two military buildings were preserved with respect to their overall space and the majority of their interior layouts. See Figure 23.

The idea proposes that parts of the University of Paris be installed within the old buildings and in the basement levels under the parade ground. See Figure 24. It aims to make the most of this Parisian heritage, taking a precise approach that will retain existing spaces and preserve the historic character of the site as much as possible.

The new activities integrate with buildings while preserving their antiquity. The parade ground retains its fundamental, unifying, and symbolic function as a landscaped forecourt leading down to define the new entry to the gallery, which required the installation of a library, a 500-seat lecture theater, 27 classrooms, a 2,000 m² library, 1,500 m² offices, and two service apartments, all incorporated into existing structures, embracing their spatial characteristics. See Figure 25 (Rohe, 2022).

The central courtyard of the complex is bounded by large structures, each with a main portion and wings. “The strategic urban function of the central courtyard is restored: once more, it is a place where flows of people come together and disperse again, and where the overall coherence of the place must be preserved, avoiding conflict between different users.” (Dalix, Chartier. Paysages, D&H, 2022).

The rehabilitated Lourcine barracks stand as a modern address on continuity and the relationship that architecture can establish between the past and the future, and develop in such a way that it accommodates the existing without driving the building to shift into conflicting configurations. See Figure 26. The project received several awards, including nominations for the Equerre d’Argent 2021, laureate Prix AMO 2021, nomination to New into Old Awards 2021, Frame Awards 2020, Audience and Jury Prize, and nomination for the Mies Van Der Rohe Award 2022. (ChartierDalix et al., 2023).

Rehabilitation approaches to revitalize historical buildings should be based on studied examples and previous experiences, as observed in our study. In Baghdad's Qishla, the approach focused on maintaining and preserving the building with all its external elements, while changing its functional nature. It was adopted as a cultural hub in Baghdad City, keeping the internal spaces as much as possible and modifying some to suit new functional needs. Some internal partitions were adjusted for certain parts. The inner courtyard of the Qishla was also revitalized to host cultural and community activities. This approach was also followed in two examples from Spain, which were also adopted as cultural centers. The project focused on documentation and restoration, addressing issues of erosion and vandalism, while adapting spaces for new uses.

As for the Lourcine Barracks in Paris, its function was changed to a university, which necessitated the construction of a new building, including an amphitheater, library, and public space. This new structure was built partially underground, ensuring that it did not interfere with the historical appearance of the barracks while remaining harmonious with the site and solving functional problems for new use. The modernization of the Lourcine Barracks utilized a precision approach, carefully adapting new functions to existing spaces and preserving the site's historic character.

In the Barcelona barracks in Spain, the building was restored to its original state, entirely preserving four of the six buildings. The building was not assigned any specific functions; instead, it was given flexible uses, ranging from cultural to training purposes, including music and theater facilities. Historical elements such as horse stables were preserved. The central courtyard has become a community garden for cultural and social festivals. The new project contains various functions that are mostly compatible with the current building without altering its form or layout, including art halls, conference centers, training centers, and cultural centers. The La Remunta Project emphasized the sustainable reuse of materials and integration with the surrounding urban context.

For the Madrid barracks in Spain, the external envelope was preserved, while a new, modern internal structure was created, clearly separating the old from the new. The new building includes a large theater, a small theater, and an exhibition hall. Notable additions to this project include focusing on the external garden, preparing it for open cultural events, and adding sustainability elements to modern buildings. The Daoíz y Velarde Centre employed a strategy of "selective intervention," preserving the exterior while radically transforming the interior and incorporating sustainable technologies.

The term 'Qishla' is a Turkish word meaning a military barracks where soldiers were stationed and not sent to war during the winter season. Today, most Ottoman-era Qishla buildings have fallen into disrepair and decay, either because of the passage of time or human encroachment. This is sometimes due to the lack of awareness among those in charge of urban development agencies in our Arab and Islamic cities about the importance of preserving such heritage buildings and the value of rehabilitating and repurposing them culturally as centers, forums, museums, and cultural exhibitions. Of the few remaining examples of 19th-century Ottoman Qishla buildings influenced by modern European architectural styles, there are very few–one can count them on the fingers of one hand, such as the Qishla in Baghdad, Damascus, Sana'a, and Benghazi (Khashbour, 2022). Benghazi Qishla is located in the center of the al-Burka neighborhood, which has become associated with the name of the Qishla, also known as the Burka Palace. Today, the Qishla are situated in the heart of Benghazi, surrounded by residential communities, vital facilities, and a network of major roads. Historically, the location of the Qasr has been distinctive and serves as a notable defensive element.

The Qishla in Benghazi, Libya, still stands in its place, resisting the ravages of time and struggling with the schemes of those who covet their land for investment. The historical significance of the Qishla al-Burka lies in the fact that it was the largest urban project implemented by the Ottomans, not only in the city of Benghazi but across Libya. It is also a part of the history of the city and some of its cultural heritage. The Qishla is a prominent architectural landmark in the fabric of the city, and for significance, it deserves research, study, preservation, and attention. By tracing the current state of the Qishla, we find that the original building dates back to the Ottoman period, with additions made during subsequent periods, including Italian and British times, and the latest Libyan additions (Khashbour, 2022). It should be noted that there were several initiatives aimed at developing the Qishla; one of the initiatives undertaken by the Libyan state was the formation of a committee in 1993 to maintain the Qishla and convert it into a historical Museum. The field study and proposal preparation stages were completed, but the work was halted. Governor Rashid Pasha began the construction of the camp during his second term (1889-1892), which was completed in 1896 during Tahir Pasha's rule. Traveler Pedretti mentioned the camp when he visited Benghazi in 1901, noting that the building was in its final stages of construction (Khashbour, 2022).

The Benghazi Municipal Hall is located in the Municipal Square, which is the main hub of the old city of Benghazi, featuring the most important commercial, religious, administrative, and banking buildings. Municipal buildings are considered the heart of Benghazi and serve as a central reference point for measuring distances to other areas, as shown in Figure 31 and Figure 32 show the Municipal Square and Municipal Hall buildings.

Almanar Palace, the Governor's Residence, or the Graziani Palace is a historic building located in the city of Benghazi, Libya. It was constructed in 1928 and 1930. The palace is situated in the center of Benghazi in an area known as Al-Khalsa Square. Architect Piacentini designed a square with a large fountain located in front of the palace. The palace is built in the Italian architectural style and is characterized by its magnificent facades adorned with carvings and decorations. It contains numerous spacious rooms and halls. The classic style of the governor’s residence was designed by three talented architects, Capitati, Alpagio, and Ferintsa. Pirazza supervised the execution of construction work (Al Faqih, 2021).

It should be mentioned that the Italian architecture during the Italian colonial period dealt with the local architectural heritage in a way that took into account homogeneity, integration, and continuity. This architectural output was in line with existing urban formations in a way that achieved the desired beauty (Safour & Elmazek, 2023). The design concept aimed to create a building suitable for the governor's residence, while ensuring protection, security, and ease of access and egress. It is also important for the building to harmonize with the local architecture and environment. The architects skillfully embodied these ideas, evident in the building's horizontal orientation, simple façades, arches, and prominent main entrance, reminiscent of the doors of Benghazi that dominate the façades of residences. There is complete harmony between the front facade and the buildings constructed at the end of the Ottoman era along Corso Italia. Figure 37 shows that the composition of the palace includes the main, and the elevations of the building also illustrate the key entrance and the back entrance.

The rehabilitation strategies applied to historic buildings should be based on the experience of other historic buildings and their outcomes. The evidential basis for rehabilitation will help ensure that the work is effective and treats built specialism for its historical value and meaning, and any best practice approach being undertaken. In the rehabilitation approach, there is a wealth of previous projects that contribute to the evidence base of their use. Architects and the conservation profession are well placed and able to reach informed decisions about the properties of the place, about the other functions, safety requirements, and still provide their conservation purpose.

Every historic building has a unique set of conditions, issues, challenges, characteristics, specific function requirements, and cultural values. For instance, the municipality building could have an approach of keeping its main building's external character but allowing the implementation of a new structure using the internal area of this significant heritage building. This would allow it to maintain the historical character of the municipality building as a key contributor to the urban landscape, and it could modernize today's necessary internal uses of a complex building.

In contrast, we may need a more extensive preservation approach for the Almanar Palace. To consider this building, our strategy may be twofold: to preserve both the interior and exterior, including the outer landscape, and then adaptively reuse the building, implementing functions that are appropriate for utilizing the space. This approach preserves the breadth of historical and architectural values and adapts them for reasonable use.

Turkish Barracks suggest an opportunity for a multilayered approach to rehabilitation. The complex structure of military buildings means that barracks can only be partially preserved, fully adapted, or not deemed to have significance either to their form or to their historic value in the community. It might make sense to acknowledge the best-preserved part of the barracks by restoring it, keeping other parts of it preserved for their significance, and making decisions about building anew where it would replace things that were so far gone or damaged that they no longer existed. In this scenario, we would aim to retain the essence of barracks' history while making decisions about its structural integrity and future use.

This study does not explicitly state its limitations. However, it appears to focus on a limited number of case studies in Benghazi and does not cover all the potential rehabilitation approaches or challenges.

While not explicitly stated in the conclusion, potential areas for further research could include detailed structural assessments of historical buildings in Benghazi and economic feasibility studies for various adaptive reuse scenarios. Moreover, future research might include community impact studies to understand the social implications of rehabilitation projects and comparative studies with other cities facing similar challenges in preserving architectural heritage.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors/individuals.

Not applicable.

The author(s) declare that there is no competing interest.