1. Is there any way to determine the specific era of an opposing civilization? You can get a general idea from the buildings/style of their cities, but even my spies can't tell me if someone is classical/renaissance or atomic/modern. 2. Does advancing in eras require the a civic from that eras, a tech from that era, either, or both? There are tons of era-based bonuses and civilizations and buildings but its difficult to determine when they come into effect. Also, seeing as there's only a handful of eras, it's hard to "play around" with when there's hours of play between advancements.