The first organ known of was already present in S. Nicoḷ in 1368, the year in which it was repaired; in 1403 a new organ was built by Maestro Nicolao ab organis de Alemania.
In 1597 Maestro Vincenzo Colonna replaced the old 15th century organ with a new one for which the case and choir loft still existing today were built. Lastly, the instrument currently fitted inside the 16th century case was built between 1778 and 1779 by Gaetano Callido, the most famous 18th century Veneto organ-maker. It has reached our times almost intact.
Its appearance was not altered to any great extent by operations carried out during the 19th century and, in any case, between 1975 and 77 it was returned to its original condition by the organ-maker Franz Zanin from Camino al Tagliamento.