I like the library as well. And I went to a tango musicians final recital/graduation ceremony in the performance hall/auditorium.
I include it in my "Architecture Taken From The Original Star Wars Series" buildings:
1) National Library = Two-Legged Desert Killing Machines ("Empire Strikes Back")*
2) Planetarium = Darth Vader's Mask (All three films)... though it also is similar to the "Legion of Doom"'s headquarters in "The Superfriends" cartoon.
3) La Mezquita de Palermo = a moder day Sultanhamet (Blue Mosque)/Hagia Sofia + R2D2 in the back of the X-Wing Fighter when he blows up the Death Star ("Star Wars" the original)
4) Banco Hipotecario (corner of Reconquista & Mitre) = Docking Bay of the Deathstar ("Star Wars" & maybe "Return of the Jedi")**
*This view is best from Av. Libertador
**This view is best from Reconquista about 30 meters from Mitre between Mitre & Peron.
This is the closet view that I could find to what I'm talking about for " ** ":