Entering the Duomo di Milano over the course of the year and looking upward in the first aisle on the right, one cannot help but notice a jute canvas hanging from the ceiling and wonder what mysteries lie beneath. That "sack" carries within it an ancient memory, one that is vivid and alive to every Milanese person who has, over the centuries, helped to engrave the history of the region's people into the Duomo's marble; a memory that the Archive of the Veneranda Fabbrica today represents and preserves, like a diary of the city since 1387, within its renovated and restored spaces. The Photo Library houses over 40,000 photo-types pertaining not only to the Cathedral and to the various restoration projects which have taken place over the years, but also to the religious and cultural initiatives that have involved the Milanese people. In fact, these photographs also immortalize the rite of the "Nivola", protected during the rest of the year under a jute canvas hung up high in the Duomo's vaults.
The characteristic elevator which goes up to the tabernacle of the Holy Nail is the most well known vestige of worship connected to this relic. Due to its strange appearance, as well as its elegant movement, similar to incense rising into the air, it was called "nube" (cloud), or more commonly “nivola”, a term mutated by dialect and consecrated with use.
The Nivola was originally moved by a system of cables and pulleys controlled by a double winch placed in a cell located at the top of the absidal vault, behind the tabernacle of the Holy Nail. This device was attributed to Leonardo da Vinci (who also grappled with the architectural challenge of the Duomo's construction, developing a plan for the dome), but it seems that the construction actually dates back to San Carlo Borromeo. In fact, according to sources it was the Cardinal who made the relic descend, showed it to the veneration of the faithful, and carried it for the first time in the procession.
In the decrees issues after his pastoral visit to the Duomo, in February of 1577, immediately prior to the inauguration of the annual procession of 3 May, Cardinal Borromeo ordered the construction of a machine which would lower the Holy Nail, according to designs created by “one of his architects”. An ancient description of the Nivola is contained within the diary of the master of ceremonies from 1583-84.
In actuality the Nivola is more or less elliptical, clad in canvas, and completely covered with oil paintings of angels flying among the clouds. At the beginning of the 18th century it was adorned with four wooden sculptures, these too depicting angels. The paintings date back to 1612, when even the Annals of the Veneranda Fabbrica del Duomo (which as of this year can be downloaded online in PDF format from the following link) mention an agreement “with Paolo Camillo Landriani, known as the Duchino, for the amount due to him for the construction of the cloud, in which one ascends to the Holy Nail”; and to pay “L.500 to engraver Gio. Battista Agnesi for the four angels carved by him for the cloud”.
The Nivola is 3m long and 2.5m wide and weighs approximately 800kg. Within there are two front facing seats, capable of accommodating a maximum of four people.
The Nivola was restored on several occasions. In 1648 a malfunction in the elevator system initially caused the Nivola to stop while temporarily suspended up high (while S.E. Cesare Monti was going to retrieve the Holy Nail) and then caused it to fall on 18 May of the same year. In 1795 it was repainted by Schiepati. Then in 1968 it was modified and modernized: the two man-powered winches (eight men per winch, appropriately synchronized) were replaced with an electrically powered system.
Currently the rite takes place on the Saturday prior to 14 September, the day of the Exaltation of the Holy Cross, and the Nivola is prepared several days before the rite in the Feriale Chapel. During those days worshippers have the chance to see it up close and observe the preparatory work: tests and checks overseen by technicians of the Veneranda Fabbrica del Duomo.