How do you increase the spell point cap as Empires?

I can't do it.  I've researched everything under Sorcery, Domination, and Imperium.  Imperium seems to be stuck at the refined learning/finances techs.  Supposedly, under one of the lore techs in Sorcery, I should be able to build some tower to produce sages, who then raise the spell point cap by 2.  I can't build any new buildings, or the sages.  I have cities at level 5, i own 2 each of air & ice shards.  I can't build any towers, no sage towers, none of those special 'shard towers'.  My spell points have been stuck at 10 for the longest time....  Am I missing something?