to the fifteenth century. In 1483, a chronicle of the convent refers to the existence of a "perfectum" organ. In service for more than thirty years ranging approximately from 1593 at least until 1629. Girolamo Diruta (1586-1589) and Giovanni Picchi are among the most famous organists of the basilica during that period. An engraving depicting the choir of the basilica made by Father Vincenzo Coronelli in 1708, shows that the basilica then had two organs on the perimeter wall of the choir that were facing one another and placed sideways on the choir stalls. The left organ was probably built by Giovan Battista Piaggia in 1732, this instrument could therefore be one of his first works. The activity, known up to now, of this Venetian organ builder extends, in fact, from 1740 to 1760, the organ he built for the Venetian church of San Giovanni Evangelista dates back to that date and has remained almost unchanged; the latter therefore served as a term of comparison to validate the attribution of that of the Frari and, above all, to allow its reconstruction in 1970. In fact, after Gaetano Callido had built the front organ (1795), this instrument was progressively abandoned, so as to reach the early seventies almost completely stripped of the metal rods. The organ on the right was built by Gaetano Callido in 1795 or 1796. Almost uninterrupted documentation from then until the early decades of the twentieth century provides information confirming that, unlike the other organ in the pair, this instrument was entrusted to qualified organ builders for ordinary maintenance and, from time to time, the organ on the right was restored with substantial respect for its authenticity. Problems regarding restoration of the two ancient organs was faced in 1969. Following construction of new organ with electropneumatic transmission (1928) by Mascioni, an organ located in the apse close to Titian's Assumption, use of the Callido organ decreased so much over time that between 1929 and 1969 there were no maintenance interventions on the original pared organs. The restoration of the pared organs was unequal. Given the good condition of conservation and integrity of the right organ, an intervention of extraordinary maintenance was all that was needed. While a more radical intervention was needed for the left organ that called for a reconstruction in the strictest sense, since there were seven façade pipes, all the internal mechanics, nine wooden