Rosario - Wikipedia Rosario, [a] officially the Autonomous City of Rosario, [b][5][6][7] is a city in central Argentina, in the south of the province of Santa Fe Located 300 km (186 mi) northwest of Buenos Aires on the west bank of the Paraná River, it is the country's third-most populous city after Buenos Aires and Córdoba With a growing and important metropolitan area, Greater Rosario has an estimated