Buenos Aires was established by Pedro de Mendoza in 1536, but was abandoned in 1541. In 1580, Juan de Garay refounded the city, which then became the capital of the Viceroyalty of the Río de la Plata. Cabeza de Vaca did not work to build up Buenos Aires.
Álvar Núñez Cabeza de Vaca Trivia: How Much Do You Know About Álvar Núñez Cabeza de Vaca?