The concert hall of the Romanian Athenee. It has a capacity of about 800 seats.
If you wonder about the paintings on the walls, you have to know that they represent various scenes of the Romanian history. I guess the most famous one is the scene of the entrance of the voivod Michael (known as "The Brave") in Alba Iulia, which does not appear in this photo.
Another thing about the Romanian Athenee: it was funded, partially, by public subscription. The plans were made by the French architect Albert Galleron.
Some (many) say it might be the finest building in town.