The eighth book: #8 La Celestina
I suppose it was bound to happen. La Celestina was translated to English in the 1600. While it has been updated, the translation still has elements that show its age, having really just been updated for spelling and the like. The language can certainly feel a bit dated.
What makes this more noticeable, and the book possibly less penetrable to me, is that the story has been set up as a conversation (similar to, for example, Plato's dialogues) or arguments. It reads as a play, with less stage directions, and makes the writing feel more static. There are long monologues and actions don't stand out as much. It's not what I've been used to reading and I feel I might have missed out on parts of it.
Still, it's an interesting story - the basics are there, but the characters are painted effectively and are interesting enough.