Sure, the upstairs is an excellent indie bookstore with a carefully chosen selection, extensive remainders, academic books and art books. But the basement, my friends, is a used-book-lover's paradise. The population surrounding Harvard Square has offered an extensive range of fiction, psychology, biography, social science, literary criticism, sci-fi, and cookbooks. The prices are slightly more than half the cover cost, which is sweet if you snag an older edition of something. They buy back but are very picky and somewhat ruthless, so check your heart at the door and take nothing personally. A very pleasant place to while away an hour and get an armload of great books for a pittance.