The Research Factory produces three outputs: Materials (to craft equipment at Forge and Wonder), Research Stones (for higher Academy research) and Historic Medals (for Council of State position promotions). Higher factory level yields higher-tier materials and more stones. Buildable at Keep 21, and each level additionally requires the matching Hospital level (raise Hospital first) -- double-gated. Producing Research Stones cannot be done while the factory upgrades. Milestones: Lv21 Lv3 materials; Lv32 Duty Officer; Lv36 Lv4 materials; Lv41 Lv5 materials. Materials: up to 8 queued, free but 2+ hours each (gem-finish is expensive -- avoid); make whatever you lack, but near Keep 33 continuously produce Dragon Scale for Achaemenidae equipment. Research Stones: little need until mid-game -- rarely bottleneck research until ~Keep 33 when the rightmost Academy category Military Advance depletes them; producible with gold+gems (100 pcs = 500,000 gold / 8,000 gems; unit cost does not rise with quantity). Increase daily stone-production limit via quests, factory level and a duty officer; increase stone-production speed ONLY via a duty officer (ordinary research-speed buffs like Intellect Crown do not help, since stones are not treated as Research). Historic Medals need general Tokens/Fragments+Gems; newer generals yield far more. Duty Officer (Lv32) raises stone limit and speed (ideal Margaret of Valois, then Stephen the Great). Cost F/L/S/O, enormous late.
Original research source: Evony Guide Wiki