Casa Calise was built in 1911 by Italian architect Virginio Colombo. It's an art nouveau beauty that was recently restored to it's full splendor in 2018.
If you go take a look, be shameless and press your face into the glass to peak through to the foyers, which are as beautiful as the building's exterior.
Then turn around and look across the street for another building by Colombo. Swipe to the fourth picture to see it.
I love these epic buildings tucked away in the chaos that is Balvanera.

Tip: This area is safe but it is still a poorer neighborhood so it's good to be aware of your surroundings if you walk here. Don't speak loudly or wave about your phone, etc.