Invisible Cities is acclaimed as a 20th Century classic from an author who died in 1985, having written a significant number of major works.
Marco Polo describes 55 curious cities that he claims to have visited, for his host Kublai Khan. The cities are portrayed in an imaginative way, he describes their souls, ethics, the behaviour of their inhabitants, as well as their physical settings and geography, but, in the end, he appears to be describing just one city: Venice. The writing, translated from Italian, is beautifully evocative, the descriptions poetic, in fact, it might be described as an extended prose poem.
I'm not sure what to make of it, actually. Calvino's purpose is obscure, there is no plot or character development, but it is a unique and singular work; I think he created his own genre!