Fantasy classical pre-Greek Sci-fi...

Yes it sounds pretty wacky, but it's a way of writing about an ideal society, as envisaged by Plato in The Republic. I started by reading the sequel, Philosopher Kings, and am now reading the first one, The Just City, by Jo Walton.

Athene decides she wants to start an experiment, conveniently in a place that will be obliterated, so it won't affect history.  Whoever prays to Athene that they can live in The Republic is magically transported to this place, followed by 10,000 children who were slaves.  Women are equal with men; there are robots doing routine work, so slaves are not needed in order for the rest of the inhabitants to be free to pursue 'excellence'.

Another twist is that the Gods Apollo and Athene are also there, incognito...

A good and thoughtful read.