Opera magazine
2025-05-06
The clock painted by Paolo Uccello for the Cathedral of Florence
A masterpiece of art and geometry from 1443
In the 1430s, the construction of the dome of Santa Maria del Fiore in Florence was completed, marking a turning point in Renaissance architecture and art. This period saw the beginning of a new phase of decoration for the cathedral, which, though Gothic in style, was enriched with Renaissance elements. Among the projects carried out during these years were the Sacristy of the Masses, Brunelleschi’s choir, the cantorie (singing galleries) by Luca della Robbia and Donatello, and the stained glass windows for the oculi of the dome's drum, commissioned from some of the greatest artists of the time.
The Opera del Duomo, which had already been overseeing the cathedral’s works since then, also commissioned civic and celebratory artworks for the side aisles, such as the famous equestrian portraits of two military leaders: John Hawkwood (Giovanni Acuto), painted by Paolo Uccello in 1436, and Niccolò da Tolentino, depicted by Andrea del Castagno in 1456. It is precisely within this context that Paolo Uccello's fresco decoration of the monumental clock face on the inner façade (counterfaçade) of the cathedral was created.
Paolo Uccello’s clock is not merely a timekeeping device—it is a work of extraordinary geometric complexity. The composition of the painted clock face, featuring a wheel (symbol of time) inscribed within a square and four smaller circles in the corners, draws from the classical Euclidean tradition, which continued to influence medieval art.
Many scholars believe that the idea for the clock originated with Filippo Brunelleschi, then master builder of the Opera del Duomo and a renowned clockmaker. The clock was installed on the cathedral’s inner façade, between the mosaic of the Coronation of the Virgin and the stained-glass rose window depicting the Assumption. Instead of adding another architectural opening, it was decided to create a mural that was both decorative and functional. Some experts suggest that the clock’s geometry may echo the shape of a “missing” rose window, although it is more likely that the artist was inspired by another wheel—the 13th-century zodiac wheel in the floor of the Baptistery, which has a nearly identical design.
The concept of time is a recurring theme throughout the decoration of the cathedral. The choice to install a mechanical clock in this context was no coincidence: at the time, sundials—which used the position of shadows to mark the hours—were still widely in use. The cathedral’s clock, in fact, seems to draw on this tradition, as suggested by its counterclockwise movement. Moreover, there was no standardized layout for the placement of hour markings on clock faces at the time.
Beyond fulfilling a practical function, the clock also carries a profound symbolic meaning. Positioned along the central axis of the nave and, further beyond, aligned with the Baptistery, it emphasizes the ideal path linking the octagon of the Baptistery to that of the cathedral’s presbytery, a path marked by the wheel motifs in the floor mosaics. This is a symbolic journey, also evoked by liturgical processions, which represents the passage of human time toward eternity.
The clock’s hand, however, dates back to a restoration in the last century. Archival documents suggested that the original hand was shaped like a comet star, so restorers based the new design on a drawing by Paolo Uccello himself, found in the stained glass window of the Nativity in the dome’s drum.
The presence of the four heads on the clock has sparked much debate. The expressive power of these figures is influenced by the heroic models and virile portraits of Donatello. The moldings surrounding them also recall the Gates of Paradise by Ghiberti, who was Paolo Uccello’s master and introduced him to the Opera del Duomo. For a long time, these figures were interpreted as prophets, a logical interpretation given the adjacent Campanile, which is decorated with sculptures of prophets and sibyls. Other scholars suggest that the four heads represent the Evangelists, with their respective iconographic attributes being identifiable in the faces. Positioned around the star of the Nativity, they would symbolize the written testimonies of the meeting between the eternity of God the Father and finite human time, spanning from the birth of Christ to His return on the Day of Judgment.
Paolo Uccello’s clock is not only an example of extraordinary technical and artistic skill, but also a testimony to the complex iconological program of the cathedral. Every element, from its geometry to the symbolic meanings of the figures, reflects the Renaissance innovation founded on the deep connection between classical tradition and Christian spirituality, making this masterpiece a profound synthesis of art and belief.