The Lymond Chronicles by Dorothy DunnettRead about the other books on the list.
The past’s not just another country, it’s a whole damn other world. Dorothy Dunnett’s hero, Francis Crawford of Lymond, spends much of his titular series as a sort of freelance intelligence agent, frequently in Scotland’s service, but often in the service of Scotland’s greater interests regardless of whatever Scotland’s current government might have to say about the subject. Lymond swings between professions—fugitive, mercenary captain, nation-builder—but he’s always a bit of a spy. It’s a stretch including him on this list, but historical fiction taken this seriously has as much world building as any work of fantasy or science fiction—and once you add in the peculiarities of Lymond’s world (the separate order of geniuses to which he and a few select other characters belong, the Dame de Doubtance, etc.), we’re practically in another universe altogether.
--Marshal Zeringue