The purpose of this article is to present a perspective regarding the rehabilitation of patrimonial buildings and sites, aiming to introduce universal accessibility without altering their identity and formal characteristics within acceptable limits, according to the vision of the researcher.

The theoretical section will highlight, define, and demonstrate the importance of universal accessibility with a precise attention to addressing the needs of people with different limitations, including mobility restrictions, low vision, hearing deficiencies, and neurodivergent conditions (Mental Health Hotline, XXXX), while respecting the features and historical value of these sites and buildings. The practical part will examine chosen examples of patrimonial buildings and sites that have been rehabilitated to be universally accessible and inclusive.

This analysis necessitates defining the concepts of accessibility and inclusion in the built environment and their integration into the context of historical sites and buildings. The approaches to rehabilitating patrimonial built environments will be analyzed through selected examples, with the aim of establishing the findings of the article presented.

The offered perspective establishes the researcher's vision regarding the connection between heritage preservation with universal accessibility, contemporary criteria. It's about responding, on one hand, to contemporary spatial requirements and intervention methods to integrate universal accessibility criteria, while, on the other hand, preserving the identity of the architectural form related to these patrimonial places.

Universal design in the built environment, urban design, and architecture aims to develop theories, principles, and solutions that enable all individuals to use the same physical spaces to the greatest extent possible. This approach applies to both indoor and outdoor environments, regardless of whether these spaces were originally designed for people with disabilities or other population groups. The core principles of universal design emphasize equal status, equal treatment, and universal accessibility for all users.

In the context of historic buildings, ensuring accessibility is essential for promoting an inclusive society. These sites hold significant cultural, social, and economic values, reflecting the identity and heritage of past societies. It is therefore necessary to make all heritage facilities, regardless of their location, accessible to all individuals, including persons with disabilities.

However, physical barriers can restrict access for certain individuals, consequently limiting their participation in cultural and everyday activities. Enhancing accessibility sensitively and appropriately not only raises awareness and appreciation of built heritage but also stabilizes the need for heritage conservation with the imperative of equal access for all.

To achieve this balance, stakeholders responsible for historic properties must guarantee the highest level of accessibility possible without compromising or altering key features and materials that define the historical significance of the site (Interior, 1992).

The principles of universal design were developed by the Center for Universal Design at North Carolina State University, USA, in order to clarify the concept of "design for all," which is largely synonymous with universal design. These principles intend to create inclusive environments that accommodate individuals of all ages, sizes, and abilities, including children, older adults, and both disabled and non-disabled individuals.

To embody these principles, the Center for Universal Design established seven fundamental principles (North Carolina State University, 1995). These principles serve as essential guidelines for designers in establishing accessibility criteria for the built environment.:

1. Equitable Use

2. Flexibility in Use

3. Simple and Intuitive Use

4. Perceptible Information

5. Tolerance for Error

6. Low Physical Effort

7. Size and Space for Approach and Use

In general, the needs of people with different disabilities can be categorized into four main groups: motor disabilities (including wheelchair users), neurodivergence, visual impairment, and hearing impairment. The needs of these groups must be taken into consideration when ensuring universal accessibility in historic buildings. However, due to the necessity of preserving heritage features, some accessibility measures may not be fully implemented, thereby minimizing the footprint of any probable interventions (Jester & Park, 2004).

In all cases, any interventions, additions, or modifications aimed at ensuring accessibility must be cautiously evaluated, considering the sensitive nature of historic buildings and sites. This involves identifying essential needs that cannot be overlooked and determining the most appropriate way to address them, which will be discussed later. Simultaneously, it is crucial to identify interventions or elements that can be replaced with alternative solutions that do not require significant alterations to the existing built environment. The goal is to achieve the highest possible level of accessibility while still respecting the sensitive nature of historic structures.

It is important to plan the necessary level of intervention, if any, to ensure universal accessibility. Consideration should also be given to whether the proposed solution should be temporary or permanent. These decisions must be made within the context of an overall accessibility strategy for the built environment. In all scenarios proposed, it is advisable to consult with existing users with disabilities, disability organizations, and relevant local authorities before finalizing an approach. (Authority, 2011)

This evaluation process leads to the classification of the needs and requirements for integrating universal accessibility into two categories:

This classification reflects the researcher's perspective and serves as the basis for the subsequent sections of this article.

However, it is important to clarify that the article does not focus on identifying the level of accessibility in historic buildings but rather emphasizes how their identity can be preserved while integrating the principles of universal design.

After identifying architectural or landscape interventions that are critical—meaning they necessitate significant modifications—the following elements must be considered: external or internal changes to address level differences through the integration of ramps and elevators, and modifications to accommodate accessible toilets, which often require architectural modifications, interventions, or the addition of new architectural elements. These interventions primarily address the needs of individuals with motor disabilities, including wheelchair users (see Paragraph 4.1.1. Critical Requirements for Motor Disabilities Individuals).

Returning to the core research question—how can accessible elements be integrated without compromising the formal identity of historic buildings and sites? —A key aspect to highlight is the commonly adopted approaches for ensuring universal accessibility.

The first is a consistent approach, in which the architectural features of adapted areas—or newly added architectural elements—remain harmonious with the formal identity of the historic site and patrimonial buildings. The second is a contrasting approach, where interventions are deliberately designed to stand out from the architectural style or original historical character of the building or site.

In both cases, the goal is to provide a broad perspective through concrete examples that reflect the diversity of contexts and countries represented. The selected examples illustrate these two main approaches to improving accessibility, representing sites from across the world and spanning a wide range of historical periods.

As discussed earlier, critical interventions in the context of historic buildings and patrimonial sites refer to modifications specifically intended to address the needs of people with motor disabilities, particularly wheelchair users. These needs are considered the most critical (compared to those of the other three user groups) because they often require substantial architectural interventions and the addition of new elements. Therefore, the examples presented for both approaches demonstrate architectural solutions designed specifically to meet this user group’s needs.

In contrast, accessibility requirements for people with visual impairments, hearing loss, or neurodivergent individuals may not require significant architectural modifications. For example, at the Palace of Versailles, reception counters are equipped with induction loops to assist visitors with hearing difficulties, and trained staff are continuously available to provide support for neurodivergent visitors when needed (Versailles, XXXX). Similarly, at the Smithsonian Institution—the world’s largest museum complex—technological solutions have been implemented to assist visitors with visual impairments, such as the Aira Access mobile information and verbal description service, which connects users to an Aira agent who provides real-time guidance and information during their visit (Institution, XXXX).

In both cases, the interventions are not considered critical because they do not involve spatial alterations, architectural interventions, or modifications to the spatial character of historic buildings and patrimonial sites. This distinction explains why the examples that follow focus on interventions where the architectural character and style of the modifications play a central role in improving accessibility within historic buildings and patrimonial environments.

Revisiting the fundamental research question of how to integrate universal accessibility into patrimonial sites and buildings while preserving their formal identity, it was previously argued that interventions should be kept to a minimum.

To guide this process, key elements that cannot be overlooked or replaced by alternative solutions were identified, such as accessible vertical circulation (ramps and elevators, when necessary), accessible sanitary facilities, and proper lighting and signage, as discussed in Section 4.

When planning potential interventions, it is essential to strike a balance between the necessary modifications for universal accessibility and the sensitive nature of patrimonial built environments. This balance ensures that any new elements are carefully considered before being added.

Successful interventions are those cases where contemporary materials and technologies are used, creating a clear contrast between the original and the new structures. This contrast allows for the distinct classification of architectural elements from two different periods.

It is through this visible distinction—rather than imitation or replication of the original style—that the true identity and origin of each architectural component are preserved.

As a result, the patrimonial identity of the site is maintained by ensuring a contrast between historical features and modern additions, enabling the site to evolve while still honoring its heritage.

The abstract of this paper was presented at the Environmental Design, Material Science, and Engineering Technologies (EDMSET) Conference –2^nd Edition, which was held on the 22^nd - 24^th of April 2025.

The article benefited from translation from Arabic and French into English, as well as language editing and clarity improvements using AI-based writing assistance tools. All ideas and results presented are original and produced by the author.

The article does not focus on identifying the level of accessibility in historic buildings but rather emphasizes how their identity can be preserved while integrating the principles of universal design.

The following principles were developed by the Center for Universal Design at North Carolina State University to guide the design of environments, products, and communications:

1. Equitable use:

The design is useful and marketable to any group of users.

2. Flexibility in Use:

The design accommodates a wide range of individual preferences and abilities.

3. Simple and Intuitive Use:

Use of the design is easy to understand, regardless of the user's experience, knowledge, language skills, or current concentration level.

4. Perceptible Information:

The design communicates necessary information effectively to the user, regardless of ambient conditions or the user's sensory abilities.

5. Tolerance for Error:

The design minimizes hazards and the adverse consequences of accidental or unintended actions.

6. Low Physical Effort:

The design can be used efficiently and comfortably, and with a minimum of fatigue.

7. Size and Space for Approach and Use:

Appropriate size and space are provided for approach, reach, manipulation, and use regardless of the user's body size, posture, or mobility.

Appendix B provides an overview of the previously discussed accessibility considerations for different user groups and their potential applications in historic buildings and patrimonial environments. These considerations are consolidated in a table corresponding to the discussion in paragraph 4.1.1, Critical Requirements for Individuals with Motor Disabilities. (Source: Author).

Regarding the term "neurodivergent" (Group B in Table 3), it refers to individuals whose brain function differs from the typical neurological pattern, affecting perception, language processing, behavior, and other cognitive functions. This includes individuals on the autism spectrum, among others.

Many conditions fall under this category, including Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), dyslexia, Tourette syndrome, dyscalculia, and Obsessive-Compulsive Disorder (OCD). https://mentalhealthhotline.org/neurodivergent-vs-neuroatypical/