Abstract:The conservation of the historic stone heritage has great importance when this material characterizes the image of a city, as it happens in Syracuse (Sicily). Its historical buildings are afflicted by a heavy state of deterioration due to the particular microclimate, to pollution and to neglect endured over time. This article reports the investigations made on limestone samples from historic façades of the city and from the neighboring quarries still in operation, in order to understand the petrographic typology, the reaction to the degradation over time, the possible maintenance and recovery interventions, and the correct applications in buildings of new construction. For this aim, bulk and surface analysis have been made both on the quarry materials and on the corresponding aged materials. It is therefore possible to define the types of rock most suitable for the use in contemporary architecture guaranteeing criteria of perfect biocompatibility. In this way a natural material can be employed in traditional and innovative uses and ensure both the sustainability of the interventions and the continuity of a consolidated tradition.

The recovery process of the building starts from a basic phase of knowledge whose roots are to be searched in the materials and of the constructive technologies employed, and it takes into account the history of the building and how it changed over the years.It is therefore necessary to examine the technological aspects by comparing both the materials and the constructive principles with those of areas having similar features, such as the fortified buildings in the south-east of Sicily. The case-study is a fortified villa designed in 1781 by Luciano Alì, an architect and builder who worked in Syracuse at the end of the 16th century.This building, consisting of a central part and four quadrangular towers at the corners, has a strong decorative impact. This study aims to identify the materials and the constructive characteristics of the building, pointing out its peculiarities and assembling an informative system based on the original documents describing the technological choices. The investigation connected to the recovery consists in the systematisation of historical, documentary and technological data and the creation of a guideline.