La Rioja, founded as City of All Saints of New Rioja, is the capital and largest city of La Rioja Province, Argentina, located in the east of the …La Rioja, founded as City of All Saints of New Rioja, is the capital and largest city of La Rioja Province, Argentina, located in the east of the province. The city and its eponymous province are named after La Rioja, a region in Spain.