陳金

Its alarming tilt is known the world over， but the identity of the architect who designed the Leaning Tower of Pisa has remained a mystery. Italian scholars now believe they have come up with the answer， having analysed a cryptic piece of stone that was embedded in the base of the monument and found in 1838 during excavations. Until now， the stone was thought to have come from the sarcophagus （石棺） of a 12th century Pisan architect called Bonanno Pisano. It bears his name in Latin. But archaeologists from the Scuola Normale Superiore， a prestigious university in Pisa， have managed to decipher a further two lines of the badly damaged inscription and think it proves that Pisano was the architect of the world famous monument. They say the lines read： “Mìrificùm qui cèrtus opùs condéns statui ùnum， Pìsanùs civìs Bonànnus nòmine dìcor” which translates as “I， who without doubt have erected this marvellous work that is above all others， am the citizen of Pisa by the name of Bonanno.”

There has been speculation （猜測） over the centuries as to who was behind the unique design of the tower. Among the most commonly mentioned names are the architects Gherardo di Gherardo and Giovani di Simone. Bonanno Pisano has also been mooted， most notably by Giorgio Vasari， the 16th century painter， architect and writer best known for his biographies of Renaissance artists.

The latest discovery would seem to support Vasaris theory. “The Latin adjective ‘cèrtus’ expresses all his pride at being the architect. Bonanno erected the tower certain of its great beauty and confident that it would be an incredible monument，” said Giulia Ammannati， who made the discovery.

An expert in paleography， the study of ancient writing， she said that because the tower suffered engineering problems from the very start， Bonannos proud inscription may have been unceremoniously dumped “amid all the building works and detritus at the foot of the tower.” Bonanno was also a sculptor and is credited with creating magnificent bronze doors for the cathedral of Monreale in Sicily as well as bronze doors for Pisas cathedral. The building of the emblematic bell tower began in 1173 but by the time the third level was finished， it was already tilting badly due to the soft sand and clay that lies beneath its foundations. Despite the pronounced lean， work resumed and it was completed in the second half of the 14th century. Galileo took advantage of its pronounced overhang， dropping objects of different weight from the top as a way of showing the constancy of gravity. But the tower kept shifting and by the early 1990s the tilt was more than five degrees from the vertical.

Urgent remedial works were carried out in which earth was removed in order to correct the tilt， steel braces were wrapped around the third storey and it was anchored to the ground with steel cables. Those efforts managed to rectify （矯正） the lean by nearly 45 centimetres （18 inches） by 2001.

Over the last two decades， engineers have managed to correct it by a further four centimetres （1.5 inches）. The tower is in fact the bell tower to Pisas Duomo or cathedral， which dominates an open space known as the Campo dei Miracoli or Field of Miracles.