Lanús is the capital of Lanús Partido, Buenos Aires Province in Argentina. It lies just south of the capital city Buenos Aires, in the Greater Buenos Aires metropolitan area. The city has a population of 212,152, and the Partido de Lanús has a total population of 453,500.

Buenos Aires, officially the Buenos Aires Province, is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of the province and the province's capital until it was federalized in 1880. Since then, in spite of bearing the same name, the province does not include Buenos Aires city, though it does include all other parts of the Greater Buenos Aires metropolitan area. The capital of the province is the city of La Plata, founded in 1882.