The bell tower of Santa Maria del Fiore was begun by Giotto in 1334, carried on after his death by Andrea Pisano, and finished in 1359 by Francesco Talenti, who created the large windows at the upper levels. The sculptural decoration of the tower is extremely rich: 56 relief carvings in two registers, and 16 life-size statues in the niches, all by Florentine masters of the l4th and l5th century (among whom Andrea Pisano, Donatello, Luca Della Robbia).

On the tower facade looking toward the Baptistery, the reliefs in the lower row depict the creation of man and woman, the beginnings of human work, and the "inventors" (according to the Bible) of various creative activities: sheep-herding, music, metallurgy, wine-making. In the upper register are the 7 planets, beginning with Jupiter at the north corner. On the other facades, in the lower register we find astrology, building, medicine, weaving and other technical and scientific endeavors. In the upper registers are: on the south, the theological and cardinal virtues; on the east, the liberal arts of the Trivium and Quadrivium; to the north, the seven sacraments. The statues in the niches represent the patriarchs, prophets and kings of Israel, and pagan sybils. The originals of all these works are in the Museum of the Opera.

Historical Information on the Bells
Found in documents conserved in the Opera di Santa Maria del Fiore and in the volumes on the churches of Florence by GIUSEPPE RICHA:

1 -The main bell is named for Santa Reparata and was made in 1475. Damaged, it was recast by Antonio Petri in 1705. It weighs 15,860 lbs.
2 -The bell called 'della Misericordia'. Damaged, it was recast by Carlo Moreni in September of 1830 and weighs 6,414 lbs.
3 -The bell called the 'Apostolica', fused in April of 1516 by Lodovico di Guglielmo and weighing 5000 lbs.
4 -The bell called 'la Beona'. There is no information as to when or by whom it was cast. Its weight is estimated at 2760 lbs.
5 -The bell used for the office of Terce; it bears the name 'Maria Anna' and again nothing is known of its history. It weighs 2152 lbs.
6 -A small bell cast November 4, 1513, weighing 1400 lbs.
7 -The smallest bell, cast in December of 1514 and weighing 1000 lbs.

Total weight: 34,586 lbs.

In 1956-1957, following the replacement of the old wooden armature that supported the bells with a metal structure, and the shift to motor-operated ringing, the Commission appointed to oversee these innovations decided to exclude future use of the five smallest bells, four of which were deposited in the space corresponding to the big windows of Giotto's Tower, while the fifth - the so-called 'Apostolica' - was set on the pavement of the bell cage itself.

In place of the bells thus 'pensioned off', five new ones were cast by the firm of Prospero Barigozzi. These are decorated with bas-reliefs by well-known sculptors, illustrating episodes from Mary's life and illustrating Marian privileges.

The bells presently in use have the following characteristics:

1: the 'Campanone' or 'Santa Reparata', of c. 5000 kg. And a diameter of 2.00 m., sounds the note LA;
2: the 'Misericordia', of c. 2500 kg., has a diameter of 1,500 m. and sounds DO:
3: the 'Apostolica', of c. 1800 kg., sounds RE. It has a diameter of 1.45m. and reliefs by Mario Moschi;
4: the 'Assunta', of 846 kg. And a diameter of 1.27m, sounds MI and has reliefs by Bruno Innocenti;
5: the 'Mater Dei', of 481 kg., has a diameter of 1.16m. and sounds SOL;
6: the 'Annunziata', of 339 kg., sounds LA and has a diameter of 0.95m.
7: the 'Immacolata', of 237 kg., sounds SI, has a diameter of 0.75m.

Each of the recast bells bears its own name and, in bas-relief, the arms of Cardinal Archbishop Elia Dalla Costa, who consecrated them in the Baptistery on June 10, 1956. They also bear the emblems of the Opera di Santa Maria del Fiore and of the City of Florence.

On the last four there are in addition Latin verses.

The electric motor that controls the ringing of the bells was completely renewed by the Opera di Santa Maria del Fiore in 2000-2001.

The ancient ringing style, going back to when the bells were four in number, is documented in the fourteenth-century codex, "Mores et consuetudines Ecclesiae florentinae" (Riccardiana Library), and varied according to the importance of the religuos occasion, just as today:

1) "ut in dominicis" (as on Sundays);
2) "ut in ferialibus diebus et in festis III lectionum" (as on weekdays and feasts having three readings);
3) "ut in festis IX lectionum" (as on feasts with nine readings);
4) "ut in summis solemnitatibus" (as on the most important solemn feastdays).

At present several bells are rung together only for liturgical celebrations involving the archbishop or the canons. Bells rung singly indicate, every day, the "Angelus" (at 7AM, noon and at sunset, the penultimate hour of the day according to the ancient canonical way of computing the hours (11PM), which invites all to recite the 'Credo' for the dying, and the first hour of the following liturgical day (one o'clock), which recalls the custom of reciting the 'Requiem' for the dead. A bell is also rung to indicate the suspension of work for the lunch break (11:30AM) and the death of a Guard Captain of the Confraternity of Mercy.

Following tradition, 'double minors' are in addition rung for several of the more important devotional moments in the life of the Cathedral: the solemn rosary in the months of May and October, the Stations of the Cross on Fridays in Lent, the Christmas Novena and for other occasions, as the Chapter may determine. The bells are not rung for single daily Masses or for other devotional functions.