Italo Calvino's invisible cities frames a series of surreal vignettes as a discourse between Marco Polo and Kublai Khan. Ostensibly, Polo is detailing cities in the Mongol empire that Kublai would be unable to visit due to the practicalities of rule. However, the descriptions aren't of real cities. Each "city" is rather a distillation of a mood or affect one could experience in a city, with fantastical details crystalized around that essence. These images are both no city and on another level, all cities.
Towards the end I started to wonder that maybe cities aren't all that great. How about a little bucolia and rusticorum! But as soon as I thought it Calvino addresses it with the city of Cecilia, where a goat herder wanders for ages trying to get out. "The places have mingled. Cecilia is everywhere. Here, once upon a time, there must have been the Meadow of the Low Sage. My goats recognize the grass on the traffic island."
A great afternoon read perfect for a layover.

I'll give this another chance. I read it rather quickly for a book club that I ended up not attending, and I just found it inscrutable and, to be honest, boring. Didn't get the experience other commenters had at all. Perhaps I read it too much like a real novel rather than like the philosophical prose poem it seems to be.
It's much more a snapshot of vibes than anything like a novel. The characters and plot really just serve as a framing device. I'd liken it to a collection Borges' fictions, less conceptually dense, but connected better thematically.
Strange. Borges is one of my favorites, which makes me more willing so read this book again.