The cathedral is located in Barangay II (Poblacion), San Fernando, La Union.

The friars moved the visita to Tanque and then to Kabaroan due to Mindanao's Moros and Visayan pintados raids.

St. William the Hermit Church was originally situated at Pindangan, now known as Barrio San Vicente.

In 1759, Augustinian friar Jose Torres convinced the two settlements to fuse into Pindangan (dry fish).

In 1873, Luis Perez (OSA) destroyed the abandoned walls due to the 1860 earthquake.

Jose Rodriguez Cabezas (OSA) renovated the convent and the church after the 1892 earthquake damages and added the bell tower.

The humble chapel, and later church, was ecclesiastically proclaimed a Cathedral in April 1970 during the canonical erection of the diocese of San Fernando and the appointment on February 6, 1970, of its first bishop, Victorino Cristobal Ligot (March 10, 1924 – September 18, 1980).

[3] La Union Bishop Artemio Rillera was laid to rest behind the altar of Saint William the Hermit Cathedral on November 22, 2011, with a con-celebrated mass officiated by Lingayen-Dagupan Archbishop Socrates B.

[4] Rillera was a missionary from the Society of the Divine Word (SVD) who died at age 69 due to severe asthma attack after saying Holy Mass at the Seminary of the Sacred Heart in San Fernando City, La Union on November 13, 2011.