William Tenn: Of Men and Monsters

Giant, technologically superior aliens have conquered Earth, but humankind survives – even flourishes in a way. Men and women live, like mice, in burrows in the massive walls of the huge homes of the aliens, and scurry about under their feet, stealing from them. A complex social and religious order has evolved, with women preserving knowledge and working as healers, and men serving as warriors and thieves.