Can't take the last city

[Xyael]

In my game, I can't have the last city (in the exploration age AND modern age), i can move in the capital like is an empty tile. I can loot the building in the city center, but I can never take the city and finish the game.

And in antiquity age, "same" issue but with the 2nd city of the last civ of the antiquity.

 

[Xyael]

I was finally able to win after making peace and then declaring war, then going to the wonder with one of my troops

 

[Yzman]

To take a city you need to take all fortified squares not just city. Sure it didn't have something left?

 

[CoconutTank]

Like Yzman says, taking a city now requires capping all of the fortified tiles, not just the city center.