os Baños started  as one of the many settlements of the town of Bay in southern Luzon. It  was then called Mainit because of the hot springs coming from Mt.  Makiling, a dormant volcano, which is located within its proximity. These  springs, which were said to have curative effects, attracted the Spaniards  especially the Franciscan friars. In 1589, Fr. Pedro Baustista established  public baths and renamed the place Los Bañ which means bathing places in  Spanish. By 1595, these friars started clearing portions around these bath  houses and constructed semi-permanent structures. A decree was promulgated  on September 17, 1615 by a Spaniard named Don Luis Villa authorizing the  Franciscan friars to govern Los Baños as a seperate town from Bay. Don  Juan Castañeda headed the first local government.

In  1671, a church which doubled as a hospital was constructed but was razed  by a fire in 1727. The existing church was constructed in 1851. A palace  was also constructed from 1879 to 1892 to serve as the residence of the  Capitan General. It was also used as a hospital in later years. It still  exists as the Agua Santa Resort.

Los Baños also became part of the lives of our national heroes. Jose  Rizal cited the town in his book El Filibusterismo and Apolinario Mabini  stayed for a while to try to cure his paralysis in the hot spring.

The  American regime saw the establishment of a military camp named Camp  Eldridge and the University of the Philippines.

College of Agriculture on March 6, 1909 whose campus became an  internment camp for war prisoners during the Japanese occupation until  their liberation in 1945