century, conflated the beginning of the Christian era with the birth of Venice as a Christian republic and affirmed Venice's unique place and role in history as an act of divine grace. As a construct, it is expressed in the frequent representations of the Annunciation throughout Venice, most notably on the façade of St Mark's Basilica and in the reliefs by Agostino Rubini at the base of the Rialto Bridge, depicting the Virgin Mary opposite the archangel Gabriel. As recorded by Marin Sanudo, structural work on the tower terminated in June 1514. The remaining work was completed by October 1514, including the gilding of the spire. Loggetta In the fifteenth century, the procurators of Saint Mark de supra erected a covered exterior gallery attached to the bell tower. It was a lean-to wooden structure, partially enclosed, that served as a gathering place for nobles whenever they came to the square on government business. It also provided space for the procurators who occasionally met there and for the sentries who protected the entry to the Doge's Palace whenever the Great Council was in session. Over time, it was repeatedly damaged by falling masonry from the bell tower as a result of storm and earthquake but was repaired after each incident. However, when lightning struck the bell tower on 11 August 1537 and the loggia underneath was once again damaged, the decision came to completely rebuild the structure. The commission was given to the sculptor and architect Jacopo Sansovino, the immediate successor to Bon as proto to the procurators of Saint Mark de supra. It was completed in 1546. The remaining three sides of the bell tower were covered with wooden lean-to stalls, destined for retail activities. These were an additional source of revenue for the procurators of Saint Mark de supra and were leased in order to finance the maintenance of the buildings in the square. The lean-to stalls were removed in 1873. Later history Throughout its history, the bell tower remained susceptible to damage from storms. Lightning struck in 1548, 1562, 1565, and 1567. On each occasion, repairs were carried out under the direction of Jacopo Sansovino, responsible as proto for the maintenance of the buildings administered by the procurators of Saint Mark de supra, including the bell tower. The work, funded from the accounts of the procurators, was typically executed by carpenters provided by the Arsenal, the government shipyards.