The Piazza San Marco is dominated by the St. Mark's bascilica and the Doge's Palace, which lie to the east. It had reached something approaching its present dimensions in the twelfth century and was partly redesigned in the sixteenth century. It is enclosed on its other three sides by the sixteenth-century Procuratire Vecchie to the north, the Procuratire Nuove to the south, and the Ala Napoleonica to the west. The Procuratire Vecchie was originally built for the Procurators of St. Mark's, Venice's highest dignitaries after the Doge. It retains in its arcaded front some sense of the Byzantine style of its predecessors. Originally by Mauro Codussi, it was reconstructed following a fire in 1512 by Guglielmo dei Girgi Bergomasco, Bartolemeo Bon the Younger and Jacopo Sansovino. It is terminated to the east by the Torre dell' Orologio (clocktower) which sits above the entrance to the Merceria, Venice's busiest pedestrian thoroughfare. This was built by Mauro Codussi from 1496-1499. The Procuratire Nuove are more classical in design and were planned by Sansovino to continue the architecture of his Libraria Sansovino. These were commenced by Vicenzo Scamozzi from 1582-1586 and completed by Baldassarre Longhena circa 1640. The Ala Napoleonica to the west replaced Sansovino's Church of San Geminiano, demolished by Napoleon in 1807. The lower two floors are in imitation of the Procuratire Nouvo and are surmounted by a heavy attic story with a relief of Roman emperors. These originally supported an enthroned Napoleon. This was removed after the Austrian occupation in 1814. At the eastern corner of the Procuratire Nouvo stands the Campanile of San Marco, commenced from 888-912, completed from 1156-1173, and subsequently restored, the final restoration being by Bartolemeo Bon the Younger from 1511-1514. It collapsed on 14 July 1902, also damaging the Loggetta built by Jacapo Sansovino at its foot. Remarkably, this event was recorded in a famous photograph. Both buildings were restored, the rebuilding being largely complete by 1912. The Logetta, originally a meeting house for the Venetian nobility, was Sansovino's first Venetian work. Its form is derivative of the Roman Triumphal Arch and its sculptures pay homage to the republic, with reliefs in the attic showing Venice as the figure of justice flanked by Jupiter and Venus. It was restored again in 1974.
Ruskin famously describes the approach to St Mark's as the viewer enters the Piazza in The Stones of Venice (1851-53) ( Works, 10.82-83).