The Biblioteca Nazionale Marciana (English: National Library of St Mark's) is a library and Renaissance building in Venice, northern Italy; it is one of the earliest surviving public manuscript depositories in the country, holding one of the greatest classical texts collections in the world. The library is named after St. Mark, the patron saint of Venice. It is not to be confused with the State Archive of the Republic of Venice, which is housed in a different part of the city.
The library was provided with a building designed by Jacopo Sansovino. The first sixteen arcaded bays of his design were constructed during 1537 to 1553, with work on frescoes and other decorations continuing until 1560. Sansovino died in 1570, but in 1588, Vincenzo Scamozzi undertook the construction of the additional five bays, still to Sansovino's design, which brought the building down to the molo or embankment, next to Sansovino's building for the Venetian mint, the Zecca. One of the early librarians, from 1530, was Pietro Bembo.
However, the library stock began to be collected before the construction of the building. For example, the germ of the collections in the library was the gift to the Serenissima of the manuscript collection assembled by Byzantine humanist, scholar, patron and collector, Cardinal Bessarion; he made a gift of his collection on 31 May 1468: some 750 codices in Latin and Greek, to which he added another 250 manuscripts and some printed books (incunabula), constituting the first "public" library open to scholars in Venice. (In 1362 Petrarch's library was donated to Venice but this collection of manuscripts, ancient books, and personal letters was lost or dispersed).