Saint Peter’s Square

• Customer: Governatorato dello Stato della Città del Vaticano
• Year: in corso
• City: Roma
• ATI Joint venture: Italiana Costruzioni spa, Fratelli Navarra srl

DISCREET BUT HIGH-PROFILE RESTORATION WORK

The restoration of the piazza that is the quintessential symbol of Christianity offers an important opportunity to draw on the experience accrued in a decade of prestigious work.

The experience acquired in ten years of activity in the restoration of historic monuments and works

of art enabled Italiana Costruzioni not only to sati- sfy the Governor of the Vatican City Stateʼs re- quests regarding the restoration of the balustrades, statues, coats of arms, twin fountains and obelisk of Saint Peterʼs Square, but also to undertake the restoration of Berniniʼs colonnade pursuant to a project which also included an ana- lysis of the state of repair and consequent restora- tion of the wooden roof, the roof tiles and the roof terraces as well as the completion of a full re-wa- terproofing initiative. The entire restoration project focused on exploiting state-of-theart technology in order to achieve the best possible results without having to set up traditional scaffolding in the square and thus blocking the passage of pilgrims visiting Saint Peterʼs Church during the project. This delicate objective was fulfilled via the use of a mobile chassis which enabled the restoration staff to work on the upper storeys of the colon- nade without causing any disturbance at ground level. Similarly, the roof of the colonnade was fit- ted with a bridge crane which enabled the restora- tion work to proceed freely leaving the square below entirely empty of building clutter. Following a deep-probing structural analysis of the entire co- lonnade, a mathematical model was generated insuch a way as to analyze the finished elements and to verify the overall and localized stability of the monument, especially in the light of the sei- smic activity which has recently affected Italy.

The 140 statues of Berniniʼs colonnade were car- ved from stone discarded during the construction of the façade. As a consequence the compact- ness, porosity and veining of the stone from which they are ma de varies considerably. This factor – together with others – has led to wide variation in the state of conservation of each statue. Other causes of the degradation of the stone are atmo- spheric agents, exposure to the elements, wind erosion, smog, the mechanical and chemical ac- tion of water, the presence of birdlife and, last but not least, the results of previous restoration pro- jects which have not only worsened the state of conservation of the works of art but also changed their aesthetic appearance. On first inspection it was clear that the twin fountains and their sur- rounding posts are made of white marble, traver- tine stone, grey granite, pink granite and cipollin marble, while the centrai obelisk is made of a mix- ture of marble, granite and cast bronzeo The obe- lisk seemed to be in a reasonable state of conservation, with the exception of the base which has been ruined by old plastering, cracks and a thick layer of dirt. On the contrary, the foun- tains were affected by various types of degrada- tion – crumbling, erosion, concretion, cracking, staining, biological furring and the effects of pre- vious restoration projects – whose seriousness differed according to their position. Generally speaking, the north fountain was more degraded than its twin, especially as far as the water collec- tion basi n was concerned (despite widespread re-plastering and the replacement of a number of internal parts). The metal elements of the posts and cordons surrounding the fountains and the obelisk also seemed to be deformed, corroded and partially mutilated. The columns and pilasters composing the two hemicycles and the plastering of the vaulted and lacunar ceilings were also con- sidered.