A major urban transformation is taking place in Kiruna, a mining town in the northernmost part of Sweden; the iron ore mine extends beneath the settlement and the mining activity will cause severe subsidence the coming decades. This will affect the town's built cultural heritage. Kiruna´s built cultural heritage is well established since the 1980´s, and a considerable part of it is ‘official heritage’, where buildings as well as built-up areas are protected by both local and national legislation. Conservation of the built cultural heritage involves challenges to the urban planning practice due to the extensive urban transformation. This paper presents an on-going case study that analyses the valuation and management of Kiruna´s built cultural heritage in the contemporary urban transformation process. The empiric material primarily consists of planning documents and media coverage. The meaning of the built cultural heritage to different stakeholders is interpreted through discourse analysis; there is a heritagisation process in which certain aspects of the built environments history becomes significant in the present due to cultural and social processes. In Kiruna there is a strong ‘authorised heritage discourse’ in which particularly older wooden buildings, associated with the town´s mining history, is reinforced as cultural heritage in the contemporary planning process. However, it is also possible to identify a de-heritagisation process in which the historic values of the ‘official heritage’ is diminished, and attributes in listed buildings being formulated as a liability to a sustainable urban transformation. There is a tendency that the built cultural heritage is managed as fixed and static entities in the urban planning, rather than as a dynamic, socially and culturally constructed phenomenon. In order to address the variety and diversity of values and meanings related to the built environment, planning methods need to be developed in order to make conscious and pertinent urban planning decisions.