In conformity with its official function in overlooking the square the content of the west fa�ade is predominantly a frontispiece to the text that is amplified in the mosaics of the interior.
A frontispiece which is not only a summary of the contents but which ratifies claims, invokes protection, insists on possession of St. Mark’s relics, speaks of triumph, rule and riches, which admonishes observance of the ethical-religious virtues (personifications of the virtues) and the ideals and regulations of civil coexistence (representations of months and trades). The main central piece is the Last Judgement whose terrible severity is mitigated by the hint of redemption in the Passion, Death and Resurrection of Christ in the lunettes at the sides. The History of the Relics of St. Mark, the Mysteries of the Life of Christ and the Last Judgement aremosaics, the other parts of the plan being sculptural cycles.

The fa�ade is divided into two orders by the terrace overlooking a copy of the quadriga of St. Mark, now housed in St. Mark’s Museum.
Each of the two orders has five great arches which in the lower part correspond to the four entrances to the atrium (from the left St. Alipius’ Gate, St. Peter’s Gate, The Main Portal, St. Clement’s Gate) and the window of the Zen chapel.
The 13th century marble facing includes several sculpted Byzantine slabs which should be seen as companion pieces on the two sides of the main portal which features two warrior saints. St. George and St. Demetrius, in the fight against evil. The next piece to the right with the Archangel Gabriel combines with the Virginon the left to form the Annunciation, which alludes to the legendary founding of Venice on 25th March 421 (Annunciation Day). Lastly, the two portrayals of the Labours of Hercules at the ends of the fa�ade are an example of how pagan themes, in the Middle Ages, were transformed into Christian terms: the mythological tale of Hercules, victorious over animal strength, became an allegory of Christian salvation. Hercules with the Boar of Erymanthus, the Angel Gabriel and St. Demetrius are Byzantine imports of the 5th, 12th and 11th centuries while the other reliefs are 13th century Venetian works.
The second group of works on the west fa�ade is also specifically Venetian and consists of reliefs of which half are ornamental and half figurative, framing the four lateral portals. Here the bas-relief, itself deriving from Byzantine forms, is associated with the background in gilded mosaic, but the content of this cornice does not seem to have great significance, especially now that the words on the Prophets’ scrolls are only minimally legible. In particular the reliefs of Angels’ heads on the right portals give the effect of purely ornamental fillers.

The sculptures of the three arch undersides that border the main portal, should be considered as a nucleus in themselves, a masterpiecec of 13th century Venetian artists trained in the Byzantine school and gradually coming under western influence from the Po Valley and France.

This decoration preserves some remains of a former fa�ade of the 11th or early 12th century, isolated pieces that seem almost lost or forgotten, while others have achieved a new iconographic value, such as the Dream of St. Mark which originally depicted the Dream of Joseph on the Eve of the Flight to Egypt. It was transferred to its present place at the end of the 19th century, thus taking on a new meaning and central importance as a representation of the dream in which St. Mark learnt from an angel that his relics would one day be housed in Venice.
Over and above the elements inherited from the older fa�ade there are plundered pieces integrated into the 13th century decorative plan which go so well with the works sculpted for the west fa�ade that they almost seem no longer extraneous.
The ‘ornamental trophies‘ make up a small part of the sculptural decoration, one of the most significant pieces being the porphyry head of a Byzantine emperor, later held to be the head of Carmagnola.