One of the most beautiful churches that you can see in Ilocos Sur is the San Guillermo de Aquitania Church in Magsingal. On July 31, 2001, the San Guillermo de Aquitania was one of the Philippine colonial churches declared by the National Museum as a national cultural treasure. The National Commission for Culture and the Arts had identified and selected it as one of 26 Spanish Colonial Era churches to be under its conservation program.
Younger than its counterpart in Laoag City by approximately 247 years, San Guillermo de Aquitania Church was built by the Augustinian Recollects in 1827. Like other Ilocos churches, it is supported by imposing buttresses. The church’s retablo is regarded as the most important examples of Baroque-influence art in the Ilocandia.