City Level Up
Your cities will level up as they hit population milestones. Level 2 - 80 Level 3 - 300 Level 4 - 700 Level 5 - 1000 Level 6 - 1500 Level 7 - 2000 Level 8 - 3000 Level 9 - 4000 You can check how many people you need to gain to reach the next level at any time on the main city interface. When a city gains a level, you get to claim the yields of any adjacent tile. Advanced city improvements will also be unlocked, so be on the lookout for new improvements in your build list.