São Borja is a city in the Brazilian state of Rio Grande do Sul. São Borja is the oldest municipality in the Brazilian state of Rio Grande do Sul and was founded in 1682 by the Jesuits as the first of the Seven Points of the Missions, and named São Francisco de Borja, in honor of Saint Francis Borgia. It is situated on the Western Frontier of Rio Grande do Sul on the border with Argentina which is defined by the Uruguai river.