The Baptistry of St. John the Baptist is found at the left side of the vestibule from the side entrance. It is here where baptisms are held. The baptismal font in bronze is the work of Publio Morbiducci. Over the font is the sculpture of Jesus being baptized by St. John . Three fishes in the form of a triangle, a fish caught in an eagle’s claws, a dove with an olive bough, and stag drinking from the fountain are brought out in relief in the baptismal font. Regular baptisms at the cathedral are usually held every Sunday, one at 10 a.m. and another at 11 a.m.

The Chapel of the Sacred Heart and the Blessed Sacrament is an excellent example of architecture and the arts combined – mosaic and sculpture – very typical of Philippine religious architecture. It is effectively used as a vehicle for the mass propagation of the faith.

The chapel is found in the area where once stood the Capilla del Sagrario of Spanish times, the chapel which also served as the parochial church of Intramuros . The Chapel of the Sacred Heart has its own altar and set of pews, signifying that other divine services of the church can be conducted here. It has images of Our Lady of Perpetual Help, a replica of Murillo’s Our Lady of the Immaculate Conception in the round, and a striking mosaic piece behind the chapel’s altar.

The mosaic by Marcello Avenali centers around Christ depicted as a King in His Throne, with a heart burning with love for all men. At the sides of Christ are two angels, each supporting small images of the Vatican and the Manila Cathedral.

The altar itself has a lovely bronze masterpiece in relief by Publio Morbiducci, showing the institution of the Holy Eucharist during the Lord’s Last Supper.