2K and Firaxis Games offer new details on Civilization VI, explaining how cities will be "unstacked" in the next installment in the beloved strategy series pioneered by Sid Meier. This two-minute video helps explain how this works, and here's part of the article:

In Civilization V, you simply queue up a build order, construct your buildings and they all live as one enormous stack within the city screen. With Civilization VI, we’ve unstacked the cities, removing all of that clutter within the city screen. So not only do you need to weigh build order in Civilization VI, but you also have to consider district adjacency bonuses and what terrains around your city center are compatible with certain Wonders. There isn’t one template for success in Civilization VI, and players need to react to the environment around them. No two games will play the same.

Combat is also affected by the Unstacking Cities mechanic in Civilization VI. As cities spread across more territory and become more exposed, adept warmongers may target specific tiles to cripple a city’s infrastructure before going after the city center. Additionally, passive players who would choose to fortify cities in the past must now consider their city’s full perimeter when deciding to pursue this same tactic in Civilization VI. A city is so much more than just its city center now.

Finally, from a visual standpoint, Unstacking Cities presents great aesthetical changes to the Civilization experience. Cities now look more diverse and reflect their growth in more distinct ways. We’ve found this change goes a long way, not only in making players feel more connected to their choices and progress, but also in keeping players immersed in the beautiful world of Civilization VI.