Thessaly, book 1: The Just City
Jo Walton2015

One day, in a moment of philosophical puckishness, the time-travelling goddess Pallas Athene decides to put Plato to the test and create the Just City. She locates the City on a Mediterranean island and populates it with over ten thousand children and a few hundred adults from all eras of history . . . along with some handy robots from the far human future.

Meanwhile, Apollo - stunned by the realization that there are things that human beings understand better than he does - has decided to become a mortal child, head to Athene's City and see what all the fuss is about.

Then Socrates arrives, and starts asking troublesome questions.