Formerly called the Banco de Londres building.
In 1959 a contest was held for the project at the invitation of the Headquarters of the Bank of London and South America. The land was located on a street corner in downtown Buenos Aires, where the financial activity was booming.
The winning design was submitted by the team Clorindo Testa, associated with S. E. P. R. A society, composed of architects: Elia Sanchez, Peralta Ramos and Agostini.
This project, for its urban architectural approach, is one of the most original, bold and far-reaching of the international architecture of the 60s. Source
Clorindo Manuel José Testa (December 10, 1923 – April 11, 2013) was an Italian-Argentine architect and artist.
Testa was one of the leaders of the Argentine rationalist movement and one of the pioneers of the brutalist movement in Argentina.[citation needed] His style as an architect has always been influenced by his artistic nature, with projects dominated by the effects of colour, tension, metaphors and plasticity; these aspects are well illustrated in his designs for the Biblioteca Nacional de la República Argentina and the Banco de Londres building in Buenos Aires. Wikipedia
Just to add to your knowledge I was born in Buenos Aires. But this project took place after my birth and after we had left the country.