Everyone will tell you that the best place to browse secondhand books in Kolkata is College Street. However, we beg to differ. College Street has lost its previous standing and mostly sells academic books (think textbooks for school and college kids). If you are looking for real finds, head to Golpark in south Kolkata. The pavements around here are dotted with bookstalls that date back several decades.
This is the best and biggest secondhand book area in town.
A word of advice - go there with some time to spare because you will only find the treasures if you browse carefully. From old books and journals to out-of-print magazines and catalogues covering every conceivable subject, they sell it all. And you will find them in different languages - English and Bengali are the most common, but there are also German, Russian, Spanish, and other European languages. The books are piled up in columns, so you have to look carefully. They only take cash, so make sure you are carrying notes.