Una pietra per l'architettura e la città. L'uso del grigio di Billiemi nella Sicilia d'età moderna e contemporanea

A STONE FOR ARCHITECTURE AND CITIES THE USE OF GRIGIO DI BILLIEMI IN MODERN AND CONTEMPORARY SICILY The centuries-old history narrated in this book uses Billiemi stone as a unique leitmotiv in tracing the continuity, hiatuses and distinctive features of architecture in Sicily between the modern period and the contemporary age. Another equally important objective is to investigate the process by which the history of the use of a building material became a social and economic epic through a system of new construction practices, rules and customs. As a construction material, Billiemi stone was second only to calcarenite and was widely employed in urban civil and religious monumental architecture for its physical and aesthetic characteristics that were similar to those of marble. Billiemi stone is characterized by its grey colour with black, yellow, brown, red, and white streaks. Darker shades are obtained by polishing, while if used for exteriors the stone facades, thus revealing a light grey colour. Billiemi stone was extracted from the homonymous quarries, as well as from those of Sant’Elia and Bellolampo (mountains rising north-west of Palermo). The opening of these quarries roughly dates back to the last decade of the sixteenth century when the early works made with grigio di Billiemi stone appeared in Palermo. Billiemi stone was a novelty compared to other imported materials, such as spolia or Carrara marble. Indeed, the economic benefits of an internal market and faster transport, as well as the expressive potential provided by the unique colour, which was fashionable for those times, are among the factors that led to a construction frenzy. This stone was discovered as part of an effort to find a cheap, competitive local building material that could contribute significantly to the construction of monumental architecture by public authorities between the sixteenth and seventeenth century to modernise the city of Palermo. The first documented use of grigio di Billiemi however dates from 1600. The stone was used for the construction of a unique central-plan religious edifice commissioned by the Spanish viceroy, namely the church of Santa Lucia al Borgo. From then on the use of Billiemi stone in sacred and civil architecture, both public and private, spread like wildfire. During this period of history spanning several centuries, the progressive and almost exclusive use of Billiemi stone in architectural projects in Palermo was determined not only by the economic advantages derived from its easy accessibility and working. Its success depended greatly on the aesthetic and structural opportunities it offered. At this time, the history of the use of Billiemi stone encountered that of the column as a structural support that established its primacy in the history of Sicilian architecture. The revival of this tradition in the modern period was ensured by the intensive exploitation of the open-air quarries on Mount Billiemi that supplied strong monoliths, almost free of competition—with few exceptions—around Sicily. Between the seventeenth and eighteenth centuries, the substantial production of compact blocks of stone allowed making countless columns to build the aisles of basilicas and the cloisters of the convents of religious orders, as well as the porticos, portals, and stables of noble palaces. The use of Billiemi stone monoliths brought about the birth and development of innovative projects that also allowed achieving an unprecedented monumental scale in Sicilian architecture and, consequently, in the city of Palermo. Some works, like the church of Sant’Ignazio all’Olivella, set dimensional and structural limits for the columns, while others tried to overcome them. In this landscape, the construction and handling of the gigantic supports of the dome-covered groined vault in the church of San Giuseppe dei Teatini (1629) marked an extraordinary milestone in the history of the use of Billiemi stone and in columnar architecture in Sicily in the modern period, as well as one of the highest peaks reached in the development of building techniques at the construction site. A number of other minor events all contributed to this broader chapter of history, fuelling the phenomenon in the centuries that followed. These included the spread of quarries, the economic activities that developed as a result of the growth of an internal market and of exports in and outside of Sicily, the saga of the master masons and the rhetoric centred on the strength and resistance of this material. In 1752 ninety columns of Billiemi stone were exported to build the ground-floor arcade of the Royal Palace in Caserta. The nineteenth century was characterised by industrial production aimed at expanding trade to foreign markets and by the birth of a field of historiography centred on the study of the mechanical and physical characteristics of local stone. In the early twentieth century the transition from the use of these monolithic blocks for structural purposes to that as slabs for walls and floors for decorative purposes marked the works of Ernesto Basile and later of those of one of his pupils, Salvatore Caronia Roberti, who was also the author of an essay on the varieties of compact limestone extracted in the Palermo area, including grigio di Billiemi, which was considered among the autarchic materials of Italian architecture. The intensive use of slabs in a wide variety of sizes, typical of monumental architecture under fascism, ultimately provided further proof of the versatility of this stone in adapting to changes in architecture and marked a period of success even in contemporary times, both in Palermo and Messina. In Messina, Billiemi stone became a major resource during the long reconstruction after the earthquake of 1908, and in particular in the construction of the Town Hall designed by Antonio Zanca and the Court House designed by Marcello Piacentini. The portico of the Post Office building in Palermo, designed by Angiolo Mazzoni, with its huge columns with reinforced concrete core and coating with massive slabs of Billiemi stone, was yet another milestone following the long tradition of columnar architecture, which was inherent in this twentieth-century edifice.