The conservation of architectural surfaces. The facades restoration of San Biagio dei Librai and San Gennaro all’Olmo churches in the historical center of Naples. Il progetto di conservazione delle superfici architettoniche. Il restauro delle facciate delle chiese di San Biagio dei Librai e di San Gennaro all’Olmo nel centro storico di Napoli

Located in the heart of the greek-Roman plant of the historical center of Naples, one the most interesting Unesco site in Italy, the churches of San Biagio dei Librai and San Gennaro all' Olmo represents both for their artistic features and for historical events, two of the most interesting religious buildings of the ancient center of the city. The paper aims to illustrate the conservation project of architectural surfaces of the facades, conducted in 2012, tracing the methodological design process and criteria behind the project, up to the operational phase of execution on site to the results of the restoration. The essay discusses the techniques used in the course of the restoration, the operational methodologies and the main choices made since the first step of investigation in situ on the historic materials (plaster, marble, stone, etc.). Starting from the shared criteria in the field of conservation, such as the material compatibility, the respect of all the historical layers, the preservation of the surface’s values of the monument, the case dealt with an opportunity to experience these principles in operating practice case.