Little Belairs, Engine Summer, by John CrowleyRead about the other entries on the list.
In the not too distant future of Engine Summer, humans have more or less settled into a post-technological society. It may be large, maze-like, and ignorant of much of human history, but its people are happy, and the oral tradition keeps the ideas of angels (the precursors who uplifted humanity) and the saints (people whose examples and parables live on) alive. Also rare for science fiction and fantasy: a sprawling, fantastical city that isn’t dystopian, nor full of unknown dangers. The outside world may be kind of a bizarre mess, but Little Belairs and its enclaves are wondrous, magical, and significantly safer.