This is the old YWCA (Young Women's Christian Association) in Pasadena, built in 1921 according to the plaque. As far as I can tell, it's not being used for anything anymore.
What a cool old building. Wonder why they close some and do not use them for anything. We had one next to the High School that I went to in SF but not as nice looking as this one. Wonder if it is still open and used.