The profile of the church facades is enclosed above by an actual crown in white marble that gives the building an airy, fragile late-Gothic finish.
The Byzantine type vaults with extrados are set in inflected arches (with busts of saints in the resulting spandrels) which externally have large jagged leaves moving in the wind alternated with busts of Prophets. At the top of each of these arches there is the statue of a saint worshipped in Venice or the personification of aVirtue. Corresponding to the centre of the main facade there is a wider arch topped by a more thrusting external profile. In the intermediate space, in a starry sky, there is a lion of St. Mark, a 19th century cast iron reproduction of the original destroyed in 1797. This more significant cusp is topped by a statue of the evangelist to whom the church is consecrated and there are six golden-winged adoring angels along the profile.
Between the arches there are high Gothic aedicules (the one in the north-west corner that also contains a bell is dated 1384 and marks the beginning of works on this part of the church). Each aedicule contains a statue: at the two ends of the west faï¿½ade, the Annunciating Angel and the Virgin of the Annunciation, repeat the layout of the relief slabs on the lower part of the faï¿½ade with an allusion to the Venetian New Year and the legendry origins of the city on 25th March 421. In the four aedicules of the west faï¿½ade are the four evangelists; in the northern flank the Fathers of the Church and in the southern two saints (Anthony the Abbot and Paul the Hermit).
Beneath the four central aedicules of the west and north sides there are robust human figures supporting wineskins, enclosed within the narrow space of the niches cut in the spandrels: these are the so-called spouts or ‘gargoyles’ that once actually conveyed rainwater from the roofs behind, evoking the concept of the Rivers of Paradise (another four rivers, now reduced to two, were in the lower 13th century part of the west facade). The high reliefs of the arch around the central window, behind the horses, also belong to the same phase: the intrados contains four Patriarchs of the Old Testament and the four Evangelists within baldachins while on the front there are events from the Old Testament in hexagonal panels alternated with foliage.
Most of the sculptural decoration – in which, among others, there is also Carrara marble – must have taken place at the time of the two documented supplies of marble from Lucca in 1414 and 1419. This leads us also to the names of the artists who were probably in charge of the enterprise: in 1414 Paolo di Jacobello dalle Masegne and in 1419 Niccolò di Pietro Lamberti from Florence.
The statues in the aedicules belong to the first or Venetian phase of the works while the St. Mark in the centre of the west facade and above all the reliefs of the central arch, full of Ghibertian references, are of the second or Tuscan phase. One of the Tuscan sculptors who worked here was Nanni di Bartolo to whom three of the spouts on the north faï¿½ade have been attributed, whereas the hypothesis that Jacopo della Quercia was involved cannot be confirmed. Four figures of saints (Constantine, Demetrius, George, Theodosius) which fell in an earthquake in 1511 were replaced in 1618 by Giorgio Albanese.