Our previous home had built-in bookcases around the fireplace. We didn't realize how much we would miss that shelf space when we moved. We've got piles of books everywhere!
As my skills and means have been progressing, I set out to make a bookshelf with strong joinery....and no plywood! I really liked a Robert Lang Craftsman bookcase I saw in Popular Woodworking #170, so rolled with it. Of course, I customized it to my tastes.