The Immaculate Conception Parish Church or the Old Oton Church, an architectural marvel during the colonial period. It is said to be the most beautiful and largest cathedral in the entire Western Visayas region during the colonial period. It was destroyed during the Lady Caycay Earthquake in 1948.
Oton became the first capital of Iloilo in 1571 during the time of Legazpi. Oton was formerly called Kagayunan a local term which means blue water. There are three stories about the origin of the town's name.
It's one hot season at the time, while the two Spaniards are walking around the town, they reached Oton. They passed by the natives who were harvesting rice. Since the two Spaniards doesn't know the name of the place, they asked the people about its name in Spanish language. The natives who doesn't know what they are saying thought that they are asking about the time. It was noon time then so they said "Ogtong-Adlaw." Thinking that "Ogtong" is the name of the place, the Spaniards keep on saying it. Since the Spaniards could not pronounce well the phoneme "ng", Ogtong became OTON.
Some of the natives are saying that during those times, the fishermen always have a plenty catch of the fish known as "kogtong" - which are plenty in the area. Kogtong is a type of fish which is six inches in length, grayish in color and can be caught only in the river. They call the place Ogtong taken from the name of the fish kogtong.
Long time ago, there's a thriving plant growing at the very shores of the river that surrounds the entire town of Oton. This plant looks like the vines or roots which are crawling at the shores of the river and when this vine is axed, its releases resin or sap which is color blood. They call this plant "batang" however it was not mentioned by Father Demetrio Cobos in his book "Apuntos Historicos" and only said that Oton came from this plant.
In the three origins mentioned, the first one is the most popular of all and usually told by the elders.