This is the Registro Civil de la Ciudad de Buenos Aires. I know this because it is written above the entrance. I also know that it was built to commemorate something, presumably the establishment of the Registro Civil, between 1886 & 1943 because these two years are written elsewhere on the façade. More I can't really tell you other than the fact that there are three very nice Art Deco lamps hanging in the entrance.
Here is the guide from the BBC World Service
59 minutes ago