!LA PLATA LA PLATA is a city in Argentina, founded in 1884 as capital of the province of Buenos Ayres, 30 m. south-east of Buenos Ayres. The Foundational Urban Area of the City of La Plata was entirely designed in 1882 as a new city, planned as a whole to serve as site of the new capital of the Province of Buenos Aires. This city was rapidly built. It has continued to grow, and has now some handsome buildings, a college, and cotton and woollen manufactures. A a canal connects it with the La Plata River.