The National Library has a long and rich history. I am not sure if all of the donations and collections from the past remain there, but at one time, it housed the collection of papers and writings from some of the great names in Argentine history.
I don't know about a lot (most) of the people who helped start and administer the library. Jorge Luis Borges, one of Argentina's famous intellectuals from the 20th century, was the director for about 20 years. Shortly after he became the director, he was told that he needed to give up reading, as he was losing his vision.
The original building was the site of the official residence of Juan Peron and his wife Evita. In 1958, they tore down the building and started the present structure. They call it "brutalist" ... most people I know just call it ugly. The mirrored windows don't help, since some are not and it gives it a patchy odd look..
This photo shows the library from the front. They made a no dogs allowed, park where you can sit and read and relax .. there is a cafe and in the main building, upstairs with great views, is another cafe.
We go there to listen to music and concerts.
Here you can see the mirrored windows look like missing teeth when they lose their mirror.
photo - shift. org
In the park behind .. under the library, is the memorial to Evita Peron. It was vandalized so many times, they have high walls around it now and the flame never burns.. but it is a pretty memorial in the park.
And that is about all I know about the Bibiloteca Nacional.