I have a question for you all re: mid-early game: do any of you build ancient city walls? I was just thinking that on my next game, after my initial expansion, I may toy around and try to pop them in before districts. I am wondering if this will save me from building extra military units to defend. Just wondering if anyone experimented with walls like that. I am a builder player, not military, hence my curiousity about building self-defending cities.
On a related note, after playing a hot seat MP game with my warmonger brother, I did notice that early attacks on AI neighbors significantly boosted his civ on all accounts, while turtling really slowed my own general development (I was the better player than he in Civ5, which is telling about Civ6's changes). I agree with all previous posters about prioritizing a strong early military for the first hundred turns to a) defend from barbars, b) explore and beat AI to CSs for envoys, and c) damage or wipe out neighbors (especially Germany, England, Japan, Aztecs, Scythia, and Kongo, who all seem to forward settle more aggressively than other AI civs).