Between the two towers, opposite the main altar of the cathedral, is the choir loft. There resides an organ, said to be one of the two oldest in Vietnam today. It was handcrafted by

foreign experts and designed specifically so that the sound is audible throughout the church, not too small or too loud.

The inside of the organ is designed similarly to a piano but is more complex. The organ also has large wooden bars that are hit against the bottom of the pipes to produce sound, similar to the way the K'lông Pút of the Central Highlands is played. However, due to lack of maintenance, the organ has been completely damaged (the wooden part of the keyboard controlled by hand has been eaten by termites). Currently, the Catholic Archdiocese of the city is also having items to renovate this organ and hope that it will be restored to its original state.

On the front between the two bell towers is a clock weighing over 1 ton made in Switzerland. Although it has been through hundreds of years, this clock works with almost absolute accuracy.