Strength of Stones

Strength of Stones is a 1981 science fiction novel by American writer Greg Bear.

Plot summary
The novel is set in a far future where cities are completely automated including the ability to move themselves. At some point in the past the cities decided that humans were not required, or wanted, and banished them, leaving their former populations to live in the wilderness. Humans see the cities as a kind of Eden, a paradise they've been expelled from. Over time, some have chosen to reject that banishment and have attempted to plunder the cities. The cities themselves also appear to be failing, perhaps because they lack an enduring purpose with no population to protect. One city has uniquely allowed a human to live inside it.