The increasing number of World Heritage Sites (WHS) since 1978 presents challenges in defining and preserving their heritage value, particularly in the face of socio-economic development and new construction. UNESCO's World Heritage Convention emphasizes the importance of Outstanding Universal Value (OUV) and the integrity of sites. Modern buildings near cultural heritage sites can negatively impact visual integrity, as evidenced by cases where WHS were delisted due to detrimental new constructions. The Historic Centre of Prague, a diverse city integrating historic and modern buildings, serves as a case study to understand the balance between heritage preservation and modernization. This study aims to investigate people's visual focus patterns concerning the integrity of the WHS to ensure traditional culture is not threatened by modern development. The primary research questions address the characteristics of visual concerns for landmark buildings, street scenes, and typical architecture and sculptures from macro, meso, and micro perspectives respectively, using eye-tracking technology to identify visual patterns and understand human visual concerns.

Existing literature highlights the challenges of defining and preserving heritage, focusing on the impact of urban development on the visual integrity of WHS. Studies emphasize the significance of OUV and the negative impacts of large-scale development on visual satisfaction. While management studies on WHS are prevalent, research exploring people's visual perceptions remains limited. Video-oculography and eye-tracking techniques have emerged as valuable methods for assessing eye movements and visual attention patterns. Previous studies have used eye-tracking to explore visual attention in museums and landscapes, revealing how visual information like size, shape, color, architectural style, and tourist density influences subjective visual attention. However, few studies have applied eye-tracking technology to analyze visual patterns related to the integrity of heritage conservation in a WHS context, emphasizing the need for this study.

This study employed a mixed-methods approach combining a field survey, space syntax analysis, and eye-tracking experiments to analyze visual focus at three scales: city, street, and building. A field survey involved taking over 200 photographs of the Historic Centre of Prague from various viewpoints, capturing different aspects of the urban landscape. Space syntax analysis, using Depthmap software, generated an axial map and visibility graph analysis (VGA) to reveal the connectivity and integration of streets. The eye-tracking experiment involved 54 participants (24 male, 30 female) with normal or corrected-to-normal vision. Participants viewed photographs from the field survey on a screen while their eye movements were recorded using a Tobii TX300 eye tracker for 10 seconds per image. Visual heatmaps were generated from the eye-tracking data to identify areas of concentrated visual attention. Statistical data analysis was performed using SPSS to identify significant patterns and relationships between visual focus and different aspects of the urban environment. The study area included various elements: the Prague Historical Reserve and its buffer zone, residential and functional utilization areas, green areas, traffic planning, air pollution areas, and flood-prone areas. The data gathered helped investigate the visual impact of these elements on visitor perception and informed recommendations for heritage conservation planning.

The study revealed several key findings about visual focus patterns in the Historic Centre of Prague. At the city scale, visual heatmaps indicated that while the buffer zone effectively maintained visual integrity around the main attractions, prominent structures like the Zizkov TV Tower still captured considerable attention. The highest points of the skyline, buildings with unique colors or styles, and prominent architectural and landscape nodes attracted the most visual attention, while greenery, large areas of roofs, and ground received less focus. At the street scale, the space syntax analysis indicated low integration for most streets but revealed visual hotspots at specific locations (e.g., Parizska Street). Eye-tracking data showed that the ends of streets, building facades with decorative elements, pedestrians' faces, and even bicycles captured significant visual attention, while the sky, ground, and vehicles received less focus. In residential streets, attention was drawn to building facades with frescoes and shop decorations, especially the most complex details. In Old Town Square, the old town hall was the main focal point, along with pedestrians' faces. Greenery in courtyards and other green spaces received minimal attention. In pedestrian zones leading to Charles Bridge, the end of the street, pedestrians' faces, and bicycles were the primary visual attractions. At the building scale, heatmaps consistently indicated that complex architectural details (e.g., building facade midlines, domes, sculptures' faces, murals) captured significant attention, while simpler elements such as the sky, ground, and greenery were less visually engaging. The same pattern was observed for roofs and buildings in Old Town Square and along the Vltava River, highlighting the focus on intricate details. The age of buildings also influenced visual focus, with older buildings attracting more attention than newer ones.

The study's findings address the research questions by revealing specific characteristics of visual concerns at different scales. The results highlight the importance of a buffer zone to protect the visual integrity of WHS but also demonstrate how tall buildings and other visually prominent structures can still impact the overall aesthetic experience. The findings underscore the significance of preserving and enhancing visual elements that attract attention (e.g., building facades, sculptures, street ends) while acknowledging the limited visual impact of elements like greenery and ground. The focus on complex architectural and artistic details suggests that the aesthetic quality of these features is crucial for maintaining the overall visual appeal and cultural significance of the site. This study is relevant to the field of heritage conservation by offering concrete insights into the visual patterns of tourists and providing a practical framework for planning and managing WHS to preserve visual integrity. The study's findings support the concept of visual impact assessment (VIA) for heritage sites and contribute to a more nuanced understanding of human perception in urban environments.

This study provides valuable insights into visual focus patterns in a UNESCO World Heritage Site, highlighting the importance of considering human visual perception in urban planning for heritage conservation. The findings emphasize the need to balance modernization with the preservation of visual integrity by carefully managing new constructions, especially high-rise buildings, and focusing on the aesthetic quality of key architectural and artistic elements. Future research could extend this study by incorporating other sensory modalities (e.g., soundscape) to provide a more holistic understanding of the visitor experience in WHS and explore the application of this methodology to other cultural and natural heritage sites. Future research should also investigate the influence of individual factors (e.g., cultural background, age, expertise) on visual attention.

This study is limited to the visual perception of the Historic Centre of Prague and only considers a specific time and season. The sample size, while sufficient for statistical analysis, could be expanded to enhance generalizability. The study focused solely on visual attention; other sensory aspects (sound, smell) could be included for a more holistic understanding. The findings may not be generalizable to all WHS, as the specific visual characteristics of different sites vary.