Three hundred sixty-one (367) years ago, “Calasiao” was founded by the Dominican Missionaries. Next to town of San Carlos City, formerly “Binalatongan”, N.P. Domingo de Gabon advocated it. Its first vicar was Father Juan Maldonado de San Pedro Martyr. Because of the controversy between the said missionaries and N.P. Sto. Domingo de Gabon then, the missionaries placed a barrier between the barrios of Gabon and Dinalaoan, the place where the Roman Catholic Church is now standing. According to the version of the missionaries, this town was named “Calasiao”. This word “Calasiao” was designated as “Lugar de Rayos” in Spanish language. At the time the missionaries left this place, N.P. Sto. Domingo de Gabon moved to the said place and a temporary church was built and advocated by him as the house of N.P. Sto. Domingo de Gabon de “Calasiao” (alias Gabon). One hundred forty-five (145) years later, the very first Roman Catholic Church was constructed by the followers of N.P. Sto. Domingo de Gabon and designated the patron saints “San Pedro Y san Pablo de Calasiao”, as advocated by Padre Mis Condullo. Later on, a destructive earthquake ruined the church. A few months passed and it was rebuilt. In 1736, a group led by Palaries of Binalatongan (now San Carlos City), burned the church.
After a few years, Padre Daimu reconstructed the church with strong materials, bricks and hard timbers with iron roof. It is 88-30 meters long, 25 meters wide and 27.30 meters high. Construction begun in 1735 and ended in 1758. It has three (3) bodies (naves). Its convent is seventy-five (75) meters long and twenty-five (25) meters wide, with two (2) churchyards at the left side and front of the church. The tower is a t the right side of the church and is made of bricks and the floors and the stairs are made of hard timber. It is thirty (30) meters high, more or less. The church convent and the tower are considered the second to the best buildings in the province of Pangasinan.
MEANING OF MUNICIPAL SEAL
Rice Field or Farmland (Yellow Green) – signifies that Calasiao is a vast land with flat terrain, which could be developed into residential, commercial or other functional areas. As farm areas, they can be easily irrigated.
Coconut Tree – signifies the abundance of coconut trees and other fruit trees in the area.
Hat (Brown) – stands for hat-making, one of the leading cottage industries in the municipality.
Pile of Bamboo (Green) – symbolizes the raw materials used in cottage industries in the municipality.
Anvil and Mallet (Gray) – represent blacksmithing, primary industries of the town residents.
Vat / Pan (Black and Gray) – symbolize puto-making, a leading occupation of the townspeople.
Fish (White) – stands for the five (5) big and wide-fishing grounds of the municipality, namely: Basasong, Anolid, Marusay, San Vicente and Bayaoas.