Built in the 16th and 17th centuries by Spanish colonial missionaries, all 4 are all included on the UNESCO World Heritage List.
Spanish colonists arrived in the Philippines in the 16th century with two main goals: getting a slice of the Pacific spice trade mainly dominated by the Portuguese, and spreading Catholicism both in the Philippines and China. They were following the order given by King Phillip II, from whom the colonized islands took their name: to occupy the islands with the least possible conflict and bloodshed.
There is still discussion about where and when the first Mass in the Philippines was celebrated. Some claim it was on a small island near Bukindon Province on Easter Sunday of 1521; others affirm it was instead celebrated in Mazaua, on the very same date; documents from the Magellan expedition back the second claim.