The Piazzetta di San Marco is not part of the Piazza but an adjoining open space connecting the south side of the Piazza to the waterway of the lagoon. The Piazzetta lies between the Doge's Palace on the east and Jacopo Sansovino's Libreria which holds the Biblioteca Marciana on the west.
Starting our perambulation at the corner near the campanile, where we left the Piazza, this (west) side is occupied entirely by the Libreria (Library) designed by Jacopo Sansovino to hold the Biblioteca Marciana (library of St Mark). Building started in 1537 and it was extended, after the death of Sansovino, by Vincenzo Scamozzi in 1588/91. The building was said by Palladio to be "the most magnificent and ornate structure built since ancient times". The arcade continues to the end of the building with cafés and shops and also the entrances to the Archaeological Museum, the Biblioteca Marciana and the National Library, which occupy the floors above.
At the end of this building is the Molo (the quay fronting the lagoon) and the adjoining building to the right is the Zecca (mint) also by Sansovino (completed 1547) and now part of the Biblioteca Marciana. Turning to the left at the end of the Libreria one crosses the open end of the Piazzetta marked by two large granite columns carrying symbols of the two patron saints of Venice. The first is Saint Theodore, who was the patron of the city before St Mark, holding a spear and with a crocodile to represent the dragon which he was said to have slain. This is made up of parts of antique statues and is a copy (the original is kept in the Doges Palace). The second (eastern) column has a creature representing the winged lion which is the symbol of St Mark. This has a long history, probably starting as a winged lion-griffin on a monument to the god Sandon at Tarsus in Cilicia (Southern Turkey) about 300 BC. The columns are now thought to have been erected about 1268, when the water was closer and they would have been on the edge of the lagoon, framing the entry to the city from the sea. Gambling was permitted in the space between the columns and this right was said to have been granted as a reward to the man who first raised the columns. Public executions also took place between the columns. The 7th Column of the Piazzetta facade of the Doges Palace marking the division between the 14th & 15th century structures.
On the far side of the Piazzetta is the side wall of the Doges Palace with gothic arcades at ground level and a loggia on the floor above. Up to the seventh pillar from the front this is the building as rebuilt in 1340, while the extension towards the Basilica was added in 1424.The capitals of the columns of the extended part are mostly copies of those in the front of the Palace. The seventh pillar is marked by a tondo (circular sculpture) of Venice as Justice above the first floor loggia. To the left of this, there are two red pillars in front of the first floor loggia, contrasting with the other pillars which are of white Istrian stone. The red pillars are made of red Verona marble. They may have framed the Doge's chair on ceremonial occasions, but it seems that important malefactors found guilty of crimes against the state would sometimes be executed there.
On the rear corner of the Doge's Palace is a sculpture of the Judgment of Solomon with the archangel Gabriel above. The sculptors are not known. Set back from this corner is the Porta della Carta, the ceremonial entrance to the palace, built in fine gothic style in 1438/43, probably by Giovanni and Bartolomeo Bon. Again, there is at the top a figure of Venice as Justice, the theme of fair judgment and justice being much emphasised on this side of the palace. Below this, the head of Doge Francisco Foscari and the lion before which he is kneeling were replaced in 1885, the originals having been destroyed on French orders in 1797. The statues on either side of the gateway represent the cardinal virtues of Temperance, Fortitude, Prudence and Charity.
Next to this, on an outside corner of the basilica of St Mark, are four antique figures carved in porphyry, a very hard red granite. They are usually known as the Tetrarchs and said to represent the four joint rulers of the Roman Empire appointed by Diocletian and were formerly thought to be Egyptian. It is now thought probable (or, at least very possible) that they represent the sons of the Emperor Constantine, praised for their loving co-operation on his death in 337, especially as the work originally stood in the Philadelphion (Place of Brotherly Love) in Constantinople, where the missing foot of one of the figures has been found.
Beyond this, in front of the South wall of the Basilica are two rectangular pillars always known as the Pillars of Acre. They were thought to be booty taken by the Venetians from Acre after their great victory over the Genoese there in 1258, but this traditional story has also had to be revised. The pillars actually came from the church of St Polyeuktos in Constantinople (524-7), and were probably taken by the Venetians soon after the fourth crusade in 1204. The ruins of this church were discovered in 1960 and it was excavated in the 1990s, when capitals were found, which matched the pillars.
Beyond these pillars,opposite the corner of the Basilica, is a great circular stone of red porphyry known as the Pietra del Bando (Proclamation Stone) from which official proclamations used to be read. It has been suggested that this may have formed part of a column on which the so-called Tetrarchs stood.
Across the water (the Bacino di San Marco) at the end of the Piazzetta can be seen the island of San Giorgio Maggiore and the brilliant white facade of Palladio's church there.