Although Ilocos Norte is mostly Roman Catholic, several other religious sects have a strong following in this area. Of these, the most notable is the Aglipayan Church, founded by Batac native Gregorio Aglipay.
Ilocos Norte is home to several famous Roman Catholic churches:
Paoay Church (St. Agustine Church) - named a UNESCO World Heritage Site in 1993.
St. William's Cathedral in Laoag - famous for its Sinking Bell Tower, found 85 meters away.
St. Monica Church in Sarrat - biggest church in the Ilocos Region.
Bacarra Church - destroyed during an intensity 7.8 earthquake in 1983, reconstructed and reinaugurated in 1984.