On January 24, 1571 , feast of St. John the Baptist, the Spanish conquistador Miguel Lopez de Legaspi founded the city of Manila . He earlier took possession of Maynilad, the native settlement of Rajah Matanda and Rajah Sulayman on May 19, 1571 and firmly established Spanish authority in the newly conquered and untrammeled turf. The historic day happened to be the feast of Santa Potenciana and to honor her, she was made patroness of the new territory. Armed with the Spanish sword and the Cross, Legaspi, in his role as conquistador, apportioned a parcel of land for the church of the new settlement under the patronage of La Purisima Inmaculada Concepcion.

For more go to Manila Cathedral History.