A silly online poll asks how you arrange your bookshelf, and gives four illustrations. By size, by color, by author, or random. The poll didn’t include the way libraries do it, by subject.
I arrange books by subject but not intentionally. I sort by size, which also sorts by subject. With only a few exceptions, architecture books are largest, auto books are second, science books are third, history books are fourth, and “misc” are small paperbacks.
Sorting by size is needed because the shelves have different heights. The largest books will only fit in one place.
Polistra's Mill 