The Saint Augustine Cathedral Parish — universally called Iba Cathedral — is the seat of the Diocese of Iba and the most prominent building in the town centre. The present structure is a mid-twentieth-century concrete church, plain by the standards of the Spanish colonial churches elsewhere in the Philippines, but it holds a steady place in local life: its plaza fills on Sunday mornings, and it serves as the ceremonial anchor of the Paynauen Festival processions each April.
The Diocese of Iba was established in 1982 and covers the entire province of Zambales plus the city of Olongapo, making this modest building the spiritual headquarters for a significant stretch of the central Luzon coast.