The Navigator - is amazing. It hits you like a ton of bricks at the end. It doesn't involve knights or pageantry or royalty. It's about people in a village who have not yet been struck by bubonic plague. It's about a visionary boy's imaginative story enacted as a time-travel quest-adventure to modern times. Think of what a medieval villager would think of a submarine, a train, or a modern-day city.
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Name of the Rose - is also pretty amazing, about a Benedictine monk who is a sleuth, who winds up investigating murders at a Franciscan monastery.