This thesis engages with sustainable cultural heritage by considering how user-produced maps may reveal new knowledge about heritage values. Through interrogating whether authorized heritage values and unauthorized heritage values are aligned, as manifested in cartographical sources, by taking the World Heritage city of Visby, Sweden as a case study. The thesis will use primary source maps produced by users and compare them to sites of authorized heritage values to determine if, and where, new and divergent heritage values may appear. By considering a bottom-up approach to cultural heritage valuation, as well as supporting the preservation of user heritage values, this thesis contributes how to sustainably plan for cultural heritage from both a social and physical perspective.            The findings from the study reveal how heritage is functioning within the city of Visby, and the larger Gotland Island, to both reenforce authorized values, as well as portray new sites of heritage values. A major feature of Visby and Gotland has to do with its many periods of heritagization, which have created a phenomenon described by the user-produced maps as several heritages existing together in a singular geographical location. The user-produced maps are therefore proved to be exceptionally rich sources for user values and trends related to heritage, and should be considered for digital preservation for scholars, learners and those preserving heritage environments into the future. This study demonstrates the usefulness of user-produced maps as primary sources, and highlights key ways in which authorized heritages may be limiting to user contributions. Therefore, initiatives to encourage users to continue to create maps related to their heritage values should be encouraged. The creation of digital maps by users has limitless potential to enrich, portray, and preserve the lived heritage realities of the users, supplementing the authorized heritage values already established.