LesB, yes, I could have left them unfinished, and yes, the reason I finished the exterior was for my aesthetics. Also, the boxes are on the edge of a wooded area (facing a grassy area), which I needed to do to in order to abide by my condo rules. And I've seen many bluebirds on the edge of this wooded/grassy area, and a few have checked out my boxes. So, I'm hopeful that they'll nest there eventually.