Among the works by Vivaldi that are preserved incompletely, the Concerto in due cori con due violini e due organi obbligati, RV 584,stands out for its musical interest and structural complexity. It is a work of sumptuous andgeometrical architecture composed to mark two special and concurrent events: the purchase - in 1737 - of a new large organ by the Ospedale della Pieta and the re-engagement of Vivaldi for a final time by this famous Venetianinstitution for foundlings as its maestro dei concer