The City of Buenos Aires was founded twice as part of the Viceroyalty of Peru (Spanish Empire). Its first foundation was in 1536, by Pedro de Mendoza. In 1541, the locals destroyed and abandoned the city due to the constant threats by the natives. Its second foundation was in 1580, by Juan de Garay.
The city planning was carried out following the same model used in the establishment of many of the cities of the New World: a checkerboard layout surrounding a main square. After the promulgation of the Bourbon Reforms by the Spanish Crown under the House of Bourbon, the city of Buenos Aires was officially established as the capital city of the newly created Viceroyalty of the Río de la Plata.

Buenos Aires is often catalogued as an European city outside of Europe -and with good reason: among other features, its rationalist urbanism is in line with the rationalism showed in the European city extensions during the 19th Century.

Since its first foundation, the city was part of the Viceroyalty of Peru (Spanish Empire) and, in contrast with Lima and other colonial squares, it was a city of little relevance.

The interest of Spain in these lands was securing and supporting the navigation of inland rivers, ensuring the land tenure, and contributing to the Spanish settlement in the territory, thus facilitating the transit between the Upper Peru region and the new Spanish territories. In this way, transit and commerce would become the city’s distinctive features of the city.

The urban center was divided into blocks, and each block was subdivided into four lots, which were then awarded to the conquerors and founders of the highest ranks. 

In spite of being the Spanish Atlantic gate to South America, the city did not showed any clear signs of development until it was declared the capital of the Viceroyalty of the Río de la Plata region in 1776, after the Bourbon reforms. This turning point allowed Buenos Aires to play an important role in the commercial activity of the region.