According to the World Tourism Organization (UNWTO) in the last three decades, tourism has been one of the largest sectors in the global economy and it continues to grow in today’s world. Tourism produced 9% of the Gross Domestic Product (GDP) and 8% of the world’s employment in 2019 and it plays a prominent role within the EU countries’ economy [1], contributing, for example, to 15% of employment in a country such as Italy and a relative 13% of Italian GDP in 2019 [2]. Cultural tourism is one of the most important segments of tourism [3] and is increasingly a major slice of the cultural sector in general [4]. Cultural tourism, which usually overlaps with the term heritage tourism, is mainly rooted in heritage resources in a local context [5] and is related to heritage management and development [6]. This particularly resonates in Europe, where heritage is considered “the oldest and most important generator of tourism” [7]. Hence, tourism has become increasingly important to local communities in terms of resources used and income produced, and, consequently, the need to sustainably develop tourism has become a primary concern [8]. Therefore, the development of a sustainable form of cultural tourism is considered a compromise between the conservation of cultural heritage, the financial benefits of local communities, and public access to the resources [9].

The relationship between heritage, tourism, and sustainable development has not always been straightforward in the policy development context and it was not explicitly mentioned until 1997 in the Agenda 21 for the Travel and Tourism Industry [10]. Setting out the priorities for sustainable development in the 21st century, it identifies tourism as a form of economic development aiming at improving the quality of life of the host community, providing a high quality of experience for the visitors, and maintaining the quality of the environment. This was further elaborated by the UNWTO, stating that “Sustainable tourism development meets the needs of present tourists and host regions while protecting and enhancing opportunities for the future” [11]. Especially for marginalized, remote, or peripheral areas, sustainability has become fundamental as the communities need to support themselves with their available resources ^[8][12][8,12]. Importantly, sustainable tourism is an overarching category and is conveniently defined to include all types of tourism (conventional or alternative forms) that are compatible with or contribute to sustainable development [13].

Although sustainability in tourism is often criticized as a vague concept, ^[14][15][14,15], Richards and Hall [8] observed that, for a viable and efficient approach to sustainability in tourism, a continuous improvement of the social, cultural, and economic well-being of communities is required, and this must be wholly integrated with the care for the environment. This statement connects the development of tourism to the three aspects that have imbued the definition of sustainability since the Brundtland report [16], namely economically, socially, and environmentally sustainable development. The recent literature has expanded this interpretation of sustainability to include cultural sustainability in tourism development ^[17][18][19][17,18,19].

2. Four Pillars of Sustainability for Cultural Tourism Development

In recent decades, the “three pillars” of the sustainability concept, namely social, economic, and environmental sustainability, have started to evolve to include culture as a fourth pillar both at international and European policy levels ^[17][18][17,18] and in research ^{[20][21][22][23]}[23,24,25,26]. As Nurse ^[21][24] suggests, culture needs to be included in the discourse around sustainability in a twofold way. On the one hand, it needs to be included in terms of how the “culture of sustainable development” has evolved into a global agenda. On the other hand, the cultural arena, not intended just as the manifestation of culture, but instead as “cultural vitality”, namely “wellbeing, creativity, diversity and innovation” ^[20][23], should be treated as one of the basic requirements of a healthy society and, finally, culture itself can be facilitated by the construct of sustainable development. Although the role of culture is growing and it has started to become acknowledged, most of the attention in sustainable tourism is still drawn toward environmental and economic issues linked to tourism development, followed by growing attention toward the social aspects of the tourism development discourse ^[24][27]. Culture as a pivotal driver for the sustainable development of tourism has been overlooked to such an extent that the definition of sustainable development preferred by the World Tourism Organization (UNWTO) on their website still lacks it. Many scholars have neglected the role of culture in the sustainable development of tourism, focusing solely on the sustainability of tourism as a means to reduce the tensions and to retain the long-term capacity of natural and human resources ^[25][28] or as a channel to contribute to sustainable use of economic, societal, and environmental resources [13]. Others [13] strictly excluded culture from the definition of sustainable tourism, such as Farrell ^[26][29], who argues that the “sustainability trinity” builds on the smooth and transparent integration of economy, society, and environment to achieve sustainable tourism, or Cater ^[27][30], who further identifies three key objectives for sustainable tourism in social, economic, and environmental goals. These limited definitions contrast with a more extended vision of sustainable tourism building equally on the four pillars of sustainable development which this research enhances and moves forward.

3. Inclusive Participation in Cultural Tourism Development

Participatory models move away from hierarchical decision making to equalize the power between all parties involved and to promote an equally desirable situation in tourism planning and development for everyone involved ^{[27][28][29][30][31][32]}[30,31,32,33,34,35]. Participation is defined as “a process of involving all stakeholders (local government officials, local citizens, architects, developers, businesspeople, and planners) in such a way that decision-making is shared” ^[33][36]. It means shifting the power of development from “external experts” and governmental bodies to citizens and local communities to allow them to share decision making, responsibilities, and, additionally, the advantages of tourism development. Generally, decision makers tend to respect the community values once a participatory approach is embraced at the stages of planning ^{[27][30][31][34]}[30,33,34,37]. Vernon et al. ^[35][38] affirm that a collaborative approach, especially in the tourism sector, should be interpreted as an interactive and iterative process of sharing experiences and ideas, as well as the means to identify and form a pool of finance and human resources among stakeholders and the local community to fulfil a specific goal. The application of participatory models in tourism is also relevant in enhancing Agenda 2030 and the Sustainable Development Goals, specifically the goals focusing on sustainable consumption and production, inclusive and sustainable growth, sustainable cities and communities, and the use of marine resources. Nevertheless, whilst collaboration and participation have been part of the tourism lexicon for a long time ^[36][37][39,40], it has always been challenging to implement collaborative principles in practice ^[38][39][40][41,42,43]. Collaborative planning can result in a complex social and political process where many interconnected and interdependent parties have to work together to develop local and regional solutions. Problems in achieving participatory planning that are commonly reported are insufficient trust between stakeholders, lack of time and resources, roadblocks to finding consensus, diffidence to share power, and disbelief about the quality of collective decisions ^{[19][41][42][43][44][45][46]}[19,20,44,45,46,47,48]. The stated problems are also relevant in the cases of participatory tourism planning. However, to ensure that the benefits of tourism are related to the needs of the hosting community and to develop support and acceptance of tourism development, community participation is highly recommended and considered necessary ^[41][20]. The goal of a participatory approach is eventually to create an equilibrium in the power differential between all parties and to forge an equally suitable situation in tourism development for all the people involved and affected ^{[28][32][44][45][46][47]}[31,35,46,47,48,49]. Participation also allows for a framework for a more equal confrontation and discussion between those who traditionally have knowledge, money, and authority, such as investors, governments, and external experts, and the host community ^[48][50]. Another rationale for the participative approach resides in its positive outcomes such as: “decision-making based on public opinion, improved decision legitimacy and quality, enhancing tourism products portfolio, generating new ideas and innovations, increased trust among stakeholders, conflict reduction, cost reduction, and efficiency, and shared responsibility” ^[49][50][51,52]. In this way, the indigenous people become the main actor and decision maker in the planning, development, and management of resources needed for the tourism industry ^[51][53]. Therefore, the quality of human capital ^{[27][30][31][52][53]}[30,33,34,54,55] such as the destination managers, local entrepreneurs, inhabitants, and NGOs, as they will be presented more in-depth in the following section, is a key precondition to successful participatory processes. For all the reasons given, many scholars and practitioners accept that sustainable tourism needs to be based on community participation as a basis for its development and, as a service industry, tourism depends to a great extent on the goodwill and cooperation of the host communities. Virtually, all analyses on tourism show that the cordiality and goodwill of the local people are estimated high on the list of positive aspects of a destination ^[54][56]. These characteristics are particularly important in cultural tourism, where the local community can be considered as an integral part of the product. The implementation of sustainable tourism activities and actions becomes the result of the consensus of the local community and stakeholders with efficient utilization of local human capital and local resources, especially those with unique value as in the case of cultural heritage, especially for cultural tourism ^[55][57]. Much research has shown that excluding local groups from decision-making processes could lead to tourism development in contrast to the preferences of some groups and lead to unsustainable tourism paths and impacts ^[56][57][58][58,59,60]. In some places such as more marginalized, rural, or peripheric areas, local communities could prefer not to attract huge businesses and big external investors to their local areas even though they could bring job opportunities and could prefer having control over local tourism activities. These types of discussions and sharing opinions from the public can only happen by promoting diversity and inclusion in participatory tourism development processes. To this end, an inclusive participatory process in practice aims to involve as many diverse social and cultural groups as possible to achieve the most diverse representation. However, this can be challenging as well.