Pazo de Raxoi ('Palace of Raxoi'; Spanish: Palacio de Rajoy) is one of the most important historic buildings of the Neoclassical era in Santiago de Compostela, A Coruña province, Galicia, Spain. It is located in Praza do Obradoiro, opposite to the Cathedral, since 1766. It was restored in 2011 by the Consorcio de Santiago and it has become the official location of the city council and regional government, as well as the local police department. Over time, this building has fallen into a poor state of conservation, in fact some areas of the walls were affected by biodeterioration. We have investigated the bacterial communities affecting several wall areas from the internal courtyard of the building where different lighting were applied in order to reduce the microbial contamination. In this study, we showed a high-throughput sequencing-based analysis using the MinION platform. By this approach, it was possible to identify the diversity of the bacterial community present on different areas of the affecting wall by the sequencing of the amplicon of almost entire ribosomal operon (about 4000 bp). The MinION approach permitted to reveal the diversity of the wall bacterial communities subjected to different lighting.