Between the central nave and the presbytery, over the left choir built by the Caniana’s around the year 1790, is placed the monumental twelve-feet Organ with two keyboards, manufactured by the famous Bergamo Pipe Organ Builders of Serassi Brothers (Fratelli Serassi) in the period of 1818-19. The instrument was labeled with the original serial number 378.
In 1844 the Serassi Brothers themselves carried out an important work of “restoration” or “rebuilding” involving the likely addition of new Stops: in such occasion they relabeled the instrument with the number 572 on a new Tag, still available as of today over the rootwood front above the keyboards.
The last work of “cleaning” and “tuning” by the Serassi manufacturer was recorded in 1858.

The design
The “Prospetto di un nuovo Organo di Dodici Piedi che si richiede nella distinta Parrocchiale Chiesa di San Martino in Alzano Maggiore” [“Prospect of a new Twelve-Feet Organ commissioned by the esteemed Parish Church of St. Martin in Alzano Maggiore”], manuscript of 1818 by Carlo Serassi presented to the Vestry-board before the signing of the contract, precisely indicates the names of the stops for which he plans to reuse the old pipes, taken from the previous Organ already existing in the Basilica.
Describing the Eco stops of the Organ, he also mentioned “Adoprerando i registri vecchi dell’Antegnati per formar tutto l’Eco, eccetto il Principale Bassi che deve essere tutto nuovo per dare al detto Organo maggior forza e piacere” [“Using the old Stops existing into the Antegnati Organ, to form the whole Echo, except for the Principal Bass (Principale Bassi) which must be completely rebuilt to give to the Organ more strength and likeability”].
The writing confirms the existence, in the Basilica of Alzano Maggiore, of an instrument built by the renown family of Brescian organ-builders Antegnati, probably dating back to the years from 1608 to 1650. Of such organ nowadays remain only two pipes scattered into the Grand’Organo stops (the G1 of the XXII (Vigesimaseconda), and the C4 of the 8' Human Voice (Voce Umana), and the uncomplete 4' Soprano Flute (Flauto Soprani) Stop (21 pipes out of 30).