On the problem of the Garisenda tower. Bruno Zanardi's point of view

For Giorgio Macchi, sit tibi terra levis

For some months now in Bologna there has been a fear that the Garisenda municipal tower, one of the symbols of the city, may collapse. This is a complex and serious problem about which there are many things to be said, with roots going back a long way. First and foremost, the absolute indifference of the Ministry, the superintendencies, the University and the professional associations to the research work carried out in 1973-exactly half a century ago-by the Central Institute for Restoration (= Icr) on “The Protection of the Monumental Heritage from Seismic Risk.” The last one carried out by Giovanni Urbani before he resigned as director of Icr with almost the same reasons as those put forward by Lucio Gambi when, three years later, in 1976, he resigned from the presidency of the Institute of Cultural Heritage of the Emilia Region, a perfect institute of studies and planning that was based, as we know, precisely in the Bologna of the Garisenda. Reasons that can be summarized for both of them in the complete disinterest of politics for those two research centers, so much so that the second one was even abolished today.

But remaining to the work of seismic risk prevention of the monumental heritage that Icr tackles in collaboration with CNR, Cresme, Enea, Enel, Ismes, the University of Rome and other bodies still, this was carried out in the form of a traveling educational exhibition to be set up with ease and very low cost, so as to make it an opportunity for theoretical and technical updating not only of superintendents, engineers, architects, and surveyors active in the technical offices of Italian regions, provinces, and municipalities, but also of professionals registered with the Orders and students of the Universities. Finally, an exhibition with which the Icr once again gave credit to its original function under the law (1240/39) as a place of research, control and coordination of the action of protection of the artistic heritage, a law still in force today, at least so the current director Alessandra Marino tells me, yet never enforced by the Ministry. But of the, then, eighty or so Italian superintendencies only two, Umbria and Puglia, requested it, nor did Regions, Municipalities, Universities and professional offices want it. The exhibition, was therefore a failure. Not, however, of Icr’s research work, but of the cultural system of public administration. And it is useless to say of the dead, injured and homeless, as of the destruction and very serious damage to monuments, buildings and property that would have been avoided, or at least reduced in number and severity if in the half-century that has passed from that 1973 to the present day the Ministry of Cultural Heritage and those of Public Works and the Environment had forced their officials to work in the organizational and technical-scientific direction of earthquake risk prevention indicated in detail by Icr in that exhibition and its catalog. A work, to give just two examples of the dozens possible, that if it had been done perhaps would have prevented the still today mysterious sudden collapse, in 1989, of the Civic Tower of Pavia that left four dead and, in 1996, that of part of the vault of the Upper Basilica of Assisi that destroyed some fundamental pages of the figurative civilization of the West, in addition to causing four other victims: not to mention, most recently, the semi-cancellation of L’Aquila, Norcia, Visso, Castelluccio, Amatrice and so on.

Organizational and technical-scientific address, that of the 1973 Icr exhibition, which mainly examined the effectiveness of historical techniques for preventing architecture from seismic risk. Techniques that are all “visible,” thus counterscarp walls, chains, buttresses, flaps, etc., the only ones, as it should be noted, whose efficiency can be seen in the long run. Earthquake-resistant techniques whose characteristic, beyond that, obvious, of prevention, is that they are often also aesthetically valuable. For all of them, think of the beautiful fourteenth-century arches that support the outer left side of the Basilica of St. Clare, in Assisi, a monument located in an area at high seismic risk but which, thanks to those principals, in the seven centuries since then has never suffered damage. And think also of the celebrated brick “spur” built in 1807 by Raphael Stern to hold in place the western part of the Colosseum’s outer ring damaged by an earthquake two years earlier, a structural intervention that has not only perfectly supported that area of the monument for a couple of centuries, but also preserved its historical image as a noble ruin. Visible consolidation techniques that, however, clash with the historicist “invisible techniques” desired by art historians and practiced by almost all of the 150,000 graduate architects in Italy, a dismaying number to say the least. So invisible consolidation techniques that inject tons of liquid cement into masonry that no one can see where they go, curbs always made of concrete to be hidden under roofs, the latter sometimes made of steel like the one in the Scrovegni Chapel imprudently left in place even after the restoration of Giotto’s frescoes carried out a few years ago by Icr, etc. Invisible consolidation techniques that have the - serious - defect of weighing down and stiffening masonry structures, often ending up causing, in the event of an earthquake, the collapse of the entire monument or residential building.

For all of them, think of Amatrice whose houses and monuments, after the terrible 2016 earthquake, are today, eight years later, largely still on the ground: from the churches of San Fortunato and San Francesco, to the Clock Tower, to the entire minor urban fabric. And speaking of towers, assuming that the Garisenda’s injuries do not result from poorly calculated, e.g., oversized “invisible concrete consolidations” that were performed especially in its base, one can recall an ultrasecular example of the intelligence and effectiveness of the techniques historically adopted for the preservation of leaning monuments, thus in danger of collapse, as is the Garisenda. Solution indicated in 1450 by Leon Battista Alberti in his “De re aedificatoria”: “When it shall happen, perhaps, that a Colossus, or a Tempietto with all the base shall go away on one illate [i.e., begin to lean]; then either you will raise it from that band, which he ruins, or you will raise him below matter from that band, which stands higher.”

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That is, proposing to also use for the Garisenda the technical solution that in 1990, half a millennium after the Genoese treatise writer wrote, was adopted by the working group coordinated by Michele Jamiolkowski, with Giorgio Macchi, Carlo Viggiani, Salvatore Settis, and other leading experts. Technique that reduced the danger of collapse of the Tower of Pisa by straightening by about half a meter the slope it had since it was erected in 1173 as the bell tower of the Cathedral. A problem of more than eight centuries hitherto never eliminated, which Jamiolkowski and his people solved by inducing the subsidence of the laying ground to the north of the Tower with Alberti’s “under-excavation” (“you will lift the matter from under him”). That is, by extracting in a controlled and programmed manner thousands of small volumes of soil north of the Tower’s foundation level (precisely the “sub-excavation”), up to a total of 38 cubic meters. A work that lasted about ten years with which, even with the help of steel hoops and tie rods, the Tower of Pisa was stabilized, if not forever, certainly for a few centuries. And here we come back to the preventive and programmed conservation of Rotondi and Urbani’s Icr, because the work in Pisa stands out as the only intervention so far concretely carried out in Italy, at least to my knowledge, of programmed and preventive conservation because it was conducted “without touching the monument,” but rather by acting on its environmental context: precisely under-excavation. And here we go from Alberti’s 1450, to the 1970s when Rotondi and Urbani’s Icr tried - in vain - to make the conservation world understand the plain truth that the conservation problem of heritage is not solved by carrying out better and better restorations, but by making sure that, by acting in a preventive and programmed way on the environment, the works have less and less need of restoration. And this is because: a) restorations do not have a preventive function, but only recognize a damage that has occurred; b) restorations always damage more or less the original work. Planned and preventive conservation that, however, ministers, mayors, superintendents, professors, etc. have all let fall by the wayside due to their historical scientific unpreparedness and planning blindness, the same ones that had made Gambi and Urbani flee from the world of protection.

What will the City of Bologna do then for the Garisenda? Will it adapt to the virtuous example of Pisa by preparing to conduct a long-standing and complex programmed and preventive conservation work on the tower, including assessing its slope in relation to the state of the terrain of the square on which it stands? Or will it make it an abstract ideological issue centered, as we read in the newspapers, on the ba-bau of climate change and the ever-present ecological transition foraged by the millions of the NRP, millions that already now amount to 4.2, just to repair passersby and neighboring buildings from the special hail that is the falling stones of the Tower? That is, will it continue to be filled with incongruous cement injections, the same ones that were drilled into the base of the Tower of Pisa in 1935, believing they would stabilize it forever, while the monument has instead since then had a steady increase in its inclination to the point of creating the dangerous conditions resolved by the happy “postalbertian” work of Michele Jamiolkowski and his colleagues who participated in the extraordinary adventure of the Tower of Pisa. Among them, I repeat, was Salvatore Settis, of whom it should be remembered that he and very few others were very closely associated with Giovanni Urbani on matters relating to conservation and restoration.

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