Comparative analysis of the current uneven situation of historical quarries associated with the UNESCO world heritage sites in Spain

Abstract Spain is one of the most prominent countries regarding UNESCO World Heritage Sites (WHS), most of which were selected to preserve unique architectonical ensembles. These sites are usually characterized by the extensive use of stone as building material, which has a dominant influence on their overall appearance and value. This paper provides an overview of the general state of the building stones and the historical source quarries associated with UNESCO WHS in Spain. Ten Spanish UNESCO WHS were selected for the study. The analysis considered two main perspectives: 1) the scientific knowledge about building stones and historical quarries; 2) their conservation state, administrative situation, and social value. The case studies revealed a highly uneven degree of knowledge of the building stones and, especially, of the quarries. The lack of specific protection, touristic promotion or outreach activities is another issue that affects historical quarries, due to low political interest, in most cases. Some key elements to guarantee the conservation of historical quarries as part of the UNESCO WHS are: administrative protection that guarantees preservation particularly of the quarry landscape, awareness about the conservation of historic faces by mining companies, reopening historical quarries for restoration of monuments, limiting the maximum extraction volume, promoting scientific studies and enhancing social perception and tourism.