I used the Extra Wide Console Bookcase plans as inspiration for my built in bookcase. I made the top width 75" with the base width at 72" to fit snuggly in the little nook in my foyer. I didn't put a back on it since I attached it to the wall. I did anchor it with several screws to both columns. Also, instead of using the small additional piece on the top, I used an 1x8 and a 1x6 to make the top. I used my Kreg jig to attach the two board together along with some wood glue.
Very tickled with the results. Once the paint is good and dry, my photos, key bowl, and coin jar along with lots of books will be put on it.