Another product of the Augustinians’ tireless evangelism, the cathedral, named after the city’s titular patron, San Guillermo el Ermitaño, is perhaps Laoag’s most prominent landmark.

Commonly referred to as Laoag Cathedral, the church stands proudly as a majestic symbol of faith and colonial heritage in the heart of the city.

Established in 1580 by Augustinian friars, the cathedral started as a modest wooden chapel. The groundwork for the current stone edifice was initiated in 1612 near the banks of a river, damaged by a hurricane in 1640, by an earthquake in 1706, and by fire in 1843, and restored and renovated in 1880, showcasing a striking Italian Renaissance style infused with Baroque influences.

The church has an unusual two-storey facade, supported by two pairs of columns on each side of the arched entrance, the top of which holds a recessed niche housing the image of San Guillermo ( Saint William ).

Inside, an arched toral separates the main altar from the nave. Upon entering, visitors are greeted by ornate retablos, capiz windows, and intricate ceiling murals that embody centuries of devotion and artistic expression.

Adjacent to the cathedral is the iconic Sinking Bell Tower, a separate structure that mysteriously sinks into the ground by about an inch each year—a phenomenon attributed to its massive foundation and the region’s soft soil.

The cathedral has played a significant role in Philippine history, having been occupied by revolutionaries in 1898 and later by American forces in 1899.

Having survived fires, earthquakes, and historical upheavals, the cathedral was officially designated in 1961 as the principal church and seat of the Roman Catholic Diocese of Laoag, which governs the ecclesiastical needs of the faithful in the province of Ilocos Norte.

Today, it continues to serve as an active place of worship and a must-visit destination for history enthusiasts, pilgrims, and architecture aficionados alike.