George Eliot’s Middlemarch is a big influence on my writing; it may be my single favorite book of all time. Sure, the plot is glacial and she’s not the liveliest stylist, but the book is a miracle of characterization. She writes real humans, warts and all, asking that vitally important question, “How do I live this life?” The book also has wonderful world-building. Yes, I realize England exists, but Middlemarch doesn’t. She builds it; she peoples it; she lays it at our feet like a diamond, a complete world, rich and fascinating. That’s my model and my goal: a full world, with people in it.
Rachel Hartman, on her "most influential literary references"
This is just one quote. Google “Rachel Hartman Middlemarch” and you will find more quotes by her about it, including this blog post on her website about the origins of Seraphina. She also mentioned Middlemarch during her keynote speech at Book Camp as an example of world-building and structure and that, even if one doesn't like it, to read it anyway for its structure and study it.
I borrowed Middlemarch shortly after her keynote, the next day in fact, if memory serves me correctly. I'm just reading it now and - I like it so far.