# AR in the Architecture Domain: State of the Art
## 8 Applications
### AR for Build Deepening and Enhancement  
There is a strict connection between understanding, knowledge, and reading of the existing environment with built enhancement. Indeed, this distinction is directly related to the different target groups to which the application of AR is addressed. Starting more broadly from the basis of the valorization of the built environment, outlined in the domains of both architecture and archaeology, there have been many applications and case studies analyzed in the last 20 years. The pioneering experiments in the early 2000s aimed to highlight some potential of AR in the reading of the archaeological heritage [161]. It is worth mentioning the ARCHEOGUIDE [40], ARICH, and ARCO projects [162]. Ten years on from these experiences, a critical AR diffusion [9] is highlighted, exploiting its relevance and adaptability, and showing the first MAR applications [43; 163]. Based on many experiments [50; 164; 165; 166; 167; 168; 169], it is possible to state that there are three primary applications of AR experimentation and development for architecture and cultural heritage:  
* Applications to improve the visitor experience in contexts in which heritage is placed, distributed, or collected. Cultural tourism is an essential economic and social contributor worldwide. This area is more related to education [170], valorization, and tourist routes in general, improving the accessibility of information in both existing and no-longer-existing urban places [171; 172] or architecture [150]. The VALUE project [173] highlights user location, multimodal interaction, user understanding, and gamification as the four main pillars of innovative built use. The authors of [167; 174] analyze the experiential aspect of in situ AR communication in cultural heritage and heritage management. The complexity of shapes and interaction with ambient light play a dominant role in AR visualization, increasing or decreasing the sense of presence [175]. Some studies investigate the impact of AR technology on the visitor's learning experience, deepening both cultural tourism and consumer psychology domains [176]. Even if many studies focused on MAR in the cultural tourism domain, few of them would explore the adoption of augmented reality smart glasses (ARSGs). [PERSON] et al. [177] contributed to highlighting the adoption of this technology in cultural tourism. The mobile capacity to merge locational instruments such as GPS and AR is helpful in guided tours and tourist storytelling, furthering the revivification of cultural heritage sites. [PERSON] et al. [178] highlight the differences in learning and user perception with or without mobile apps, underlining the improvement in the cultural experience. This aspect has also been deepened by [PERSON] et al. [4], who studied the experiential value of AR on destination-related behavior. They investigated how the multidimensional components of AR's experiential value support behavior through AR satisfaction and experiential authenticity. In general, AR contributes to cultural dissemination and perception of tangible remains, while offering virtual reconstructions and complementary information, sounds, images, etc. That capacity, well known and applied in the cultural heritage field, can be enlarged in other domains and territories, i.e., attracting people to rural areas, and improving their social and economic situation [179];
* To visualize the reconstructive interventions or the simulations of intervention on the artifacts. This second domain is undoubtedly addressed to experts or technicians in the field, who are called to read the built environment and manage it in the best possible way, planning any intervention operations. This activity can be conducted at the urban scale by introducing decision-making and participatory processes--as the SquareAR project has shown [180]--or at the architectonic scale, showing the use of AR as a tool for reading the building to support the restoration process [181];
* To optimize and enrich the management and exploration of the monuments.