Sacred places are significant landmarks in Italian art cities and villages. They serve as a reference for believers and as a place of memory for the local community. However, the cultural richness of well-known churches is often at risk due to excessive tourism. Many monumental churches are merely seen as must-see places by external visitors, similar to secular monuments or museums, rather than being viewed as living religious sites. This mass tourism negatively impacts the sustainability of churches and often leads to modifications in the use of spaces to meet tourists’ needs. This paper explores the architecture of sacred places that attract high tourist traffic. The paper analyzes three Italian churches from three tourist cities of different sizes: Santa Maria Novella in Florence, the Metropolitan Cathedral of Santa Maria Assunta in Siena, and Santa Maria Assunta in Volterra. It examines how they engage tourists, the museum-like signs, and considers the cultural significance of these sites and their impact on the urban environment. Currently, these churches live a sort of dichotomy between musealization of the site and place of religion. The paper sustains that a well-designed interior setup might contribute to the Sustainable management of the heritage and be part of the Open space for culture, answering two indicators of the strategic area Environment and Resilience of the UNESCO’s Culture 2030 Indicators (Sustainable Development Goals).