To convey the republic's wealth and power, the original brick façades and interior walls were embellished over time with precious stones and rare marbles, primarily in the thirteenth century.

The great entry portal may also date to the early church as well as the western portion of the crypt, under the central dome, which seems to have served as the base for a raised dais upon which the original altar was located.

[8][13] It was at this time, however, that the tomb of Saint Mark, located in the main apse, was surmounted with brick vaults, creating the semi-enclosed shrine that would later be incorporated into the crypt when the floor of the chancel was raised during the construction of the third church.

[15] Venice was similarly interested in demonstrating its growing commercial wealth and power, and probably in 1063, under Doge Domenico I Contarini (in office 1043–1071), St Mark's was substantially rebuilt and enlarged to the extent that the resulting structure appeared entirely new.

To accommodate the height of the existing great entry, the vaulting system of the new narthex had to be interrupted in correspondence to the portal, thus creating the shaft above that was later opened to the interior of the church.

[16] Work on the interior began under Selvo, who collected fine marbles and stones for the embellishment of the church and personally financed the mosaic decoration, hiring a master mosaicist from Constantinople.

[30] The walls were pierced by windows set in larger blind arches, while the intervening pillars were adorned with niches and circular patere made of rare marbles and stones that were surrounded with ornamental frames.

[32] With few exceptions, most notably the juncture of the southern and western crossarms, both the exterior and interior of the church were subsequently sheathed with revetments of marble and precious stones and enriched with columns, reliefs, and sculptures.

[39] But many of these windows were later walled up to create more surface space for the mosaic decoration, with the result that the interior received insufficient sunlight, particularly the areas under the galleries which remained in relative darkness.

[42] Also, in the first half of the thirteenth century, the original low-lying brick domes, typical of Byzantine churches, were surmounted with higher, outer shells supporting bulbous lanterns with crosses.

[49] In addition to the reliefs in the spandrels, the sculpture at the lower level, relatively limited, includes narrow Romanesque bands, statues, and richly carved borders of foliage mixed with figures derived from Byzantine and Islamic traditions.

[note 2] The intervening aediculae with pinnacles house figures of the Four Evangelists and on the extremities, facing one another, the Virgin and the Archangel Gabriel in allusion to Venice's legendary foundation on the 25 March 421, the feast of the Annunciation.

[55] Culminating in the Last Judgment over the main portal, the sequence of mosaics in the lateral lunettes of the upper register present scenes of Christ's victory over death: from left to right, the Descent from the Cross, the Harrowing of Hell, the Resurrection, and the Ascension.

[59] In the mid-thirteenth century, they were installed prominently on the main façade of St Mark's as symbols of Venice's military triumph over Byzantium and of its newfound imperial status as the successor of the Byzantine Empire.

Between 1503 and 1515, the entry hall was transformed into the funerary chapel of Giovanni Battista Cardinal Zen, bishop of Vicenza, who had bequeathed a large portion of his wealth to the Venetian Republic, asking to be entombed in St Mark's.

[104] Directly above the bronze font, designed by Sansovino, the dome contains the dispersion of the Apostles, each shown in the act of baptizing a different nationality in reference to Christ's command to preach the Gospel to all people.

The cabinets, used for storing reliquaries, monstrances, vestments, and liturgical objects and books, were inlaid by Antonio della Mola and his brother Paolo and show scenes from the life of Saint Mark.

[127] The specific events in the lives of the various Apostles and the manner of their deaths adhere to Western traditions, as narrated in Latin martyrologies that derive in part from the Book of Acts but to a greater extent from apocryphal sources.

However, the single representations and the overall concept of presenting the lives of the saints in a composition that combines several events together in one scene have their parallels in Greek manuscript illustrations of the middle-Byzantine period.

[42] Unlike in middle-Byzantine churches where the theme of the Last Judgement is often represented in the narthex, the decorative programme narrates the stories of Genesis and Exodus: the main subjects are the Creation and the Tower of Babel along with the lives of Noah, Abraham, Joseph, and Moses.

[132] Special emphasis is given to the stories of the sacrifice of Abel and the hospitality of Abraham, located prominently in the lunettes on either side of the entry to the church, due to the analogies with Christ's death and the Eucharistic meal.

[137] The narration begins in correspondence to the former southern entry of the church with the Dome of the Creation, which opens with the spirit of God hovering above the waters and concludes with Adam and Eve cast out from the Garden of Eden.

[146] The most important period of decoration was the twelfth century when Venice's relations with Byzantium alternated between political tensions that limited artistic influence from the East and moments of intense trade and cooperation that favoured the Venetians' awareness of eastern prototypes as well as the influx of Byzantine mosaicists and materials.

[148] In succeeding phases of work in the choir chapels and the transept, Byzantine miniatures were copied more or less faithfully for the mosaics, but any eastern influence that could reflect the latest artistic developments in Constantinople is hardly traceable.

Although some activity must have still been underway in 1308 when the Great Council allowed a glass furnace on Murano to produce mosaic material for St Mark's during the summer, by 1419 no competent mosaicist remained to repair the extensive damage to the main apse and western dome caused by a fire that year.

[157] Other Florentine artists, including Andrea del Castagno, were also active in St Mark's in the mid-fifteenth century, introducing a sense of perspective largely achieved with architectural settings.

[176] St Mark's ceased to be the private chapel of the Doge as a result of the fall of the Republic of Venice to the French in 1797, and the primicerius was required to take an oath of office under the provisional municipal government.

[179][180] Documents also record the use of other instruments for liturgical celebrations, including violins, violas, viole da braccio, violoni, theorbos, cornetts, sackbuts, bassoons, and later flutes, trumpets, and oboes.

[190] This division of the choir into parts and their physical separation, coro spezzato, was integral to the Venetian polychoral style, the development of which was favoured by the particular acoustic qualities of St Mark's.

[192] It originated in the early sixteenth century in several cities of the Venetian mainland, including Padua, Bergamo, Treviso, and was introduced into St Mark's by Adrian Willaert who was nominated choirmaster in 1527 at the behest of Doge Andrea Gritti.