The Casa Rosada sits at the eastern end of the Plaza de Mayo, a large square which since the 1580 foundation of Buenos Aires has been surrounded by many of the most important political institutions of the city and of Argentina.

Its 1713 replacement by a masonry structure (the "Castle of San Miguel") complete with turrets made the spot the effective nerve center of colonial government.

Sarmiento also authorized the construction of the Central Post Office next door in 1873, commissioning Swedish Argentine architect Carl Kihlberg, who designed this, one of the first of Buenos Aires' many examples of Second Empire architecture.

It was replaced in 1713 by a more solid construction with turrets, sentry boxes, a moat and a drawbridge that upon being completed in 1720 was given the name of "Castillo San Miguel" (St. Michael's Castle).

It is the first public building of great size built by the young mercantile State of Buenos Aires; its semicircular shape had five floors for depots and fifty one storage rooms with arched ceilings, surrounded by loggias.

From the central tower at the top of which there was a clock and a beacon, stretched out a 300 m pier providing wharfaging for ships of greater draught to cast their anchors.

[2] President Domingo Sarmiento ordered the construction of the Postal headquarters in 1873 on open ground that had remained after the south wing of the Buenos Aires Fort had been demolished.

It proposed the demolition of the Fort and the construction of another building, identical to the post office, differentiating it by incorporating a long balcony on the first floor for the use of authorities during public festivities and parades.

The original structure consists of packwalls of varying thickness and slabs supported by brick counter ceilings with steel or wood roof lines, according to the sector.

The administration of Macri reordered the busts under the supervision of the National Academy of History of Argentina, and Alberto Fernández restored the order set by Cristina Kirchner.

President Javier Milei added the bust of Carlos Menem, gathering it next to Mitre, Pellegrini, Sarmiento and Roca, while those of Kirchner and Alfonsín were moved away.