I see so many videos of people doing timelaspes like it was in game. How do you watch your country's history as a timelapse?
The timelapse feature comes with the Mare Nostrum DLC. If you do own this DLC, then it should appear as a small eye icon in the top right of the interface as shown in the images below. Otherwise you'll have to buy the DLC.
There used to be a fan-made savegame replayer, but I believe it was discontinued a while ago, even before the Mare Nostrum DLC was released.