This monumental instrument is nowadays considered as the biggest and most important playable neoclassical organ of Spain.
It was built in 1954 by the company OESA from Azpeitia (province of Guipuzcoa) thanks to a legacy of Fermín De Lasala, Herzog of Mandas. This instrument is complemented with a choir organ installed in the chancel (Eco). Both instruments are playable simultaneously from the respective console thanks to the electric action.
In 2007 it was reinaugurated after a comprehensive restoration by Bernal-Korta from Azpeitia. In the course of this restoration the basic characteristic features of this beautiful instrument were respected, nevertheless the old console was substituted by a new one with a state of the art combinator.
It has five manuals with a span of 61 keys (C-c4) and pedal with 30 keys (C-f1). The total number of stops is 125.
