An Australian public library has had a book returned an estimated 150 years late after being found behind a wall during a home renovation. View image in fullscreen The book was marked as No 506 in the library’s original collection of about 1,000 books. Library rules in the 1870s stated that a book had to be returned and an overdue debt paid before another book could be borrowed. The returned book will be displayed in the library’s local history collection. We don’t want to wait another 150 years for this book to be returned,” Hudson said.