There are more than a dozen chapels inside the church of San Agustin with altars from various periods and architectural styles (baroque and neoclassical) with dedicatees varying over time depending on their patrons and changes done by the friars.

It was the practice in previous centuries that the mortal remains of, usually, prominent persons were buried inside the church. This was so since these families were patrons or benefactors who, in one way or another, contributed to its construction, donated precious jewels, saints, vestments and other church decorations or even paid for the upkeep of a chapel. In some instances, they sponsored the priests who were assigned there. In some other instances, they paid for the chapel or a slot for their final resting place.

At the far end of the church interior is the presbitery where one can find the altar mayor or main altar. It is made of carara marble and was installed in 1934 which replaced the original made of wood.

The huge retablo just behind it catches the eye. Its top is crowned by the image of the Holy Spirit in the form of a dove with Saint Augustin at the lower center dressed in white robes flanked by two angels. The grand niche contains the statue of St. Paul.

Trompe l’oeil is French for fools the eye. It first appeared in the Philippines in San Agustin church in Intramuros where the ceilings and walls are decorated with it. At first, one would think that these are carved decorations, a perfect play of light and shadows until upon close scrutiny, the three dimensional effect, are infact just painted on the ceiling.

A look inside San Agustin church is a look into the grandeur of a bygone era as well as the power that the Catholic church wielded during the Spanish colonial years. One is only awed with amazement gazing at these ornate and fabulous richness and artistry.

San Agustin Church in the Agustinian monastery complex in Intramuros is undeniably, the mother of all churches being the oldest in the country despite claims from other places. Constructed from 1587 - 1607, it has survived earthquakes, typhoons, the British Invasion, the Philippine Revolution and World War II, which, was the only building left standing in Intramuros.