I don't think the one in the screen we have seen is as big, the others on the map compared do give the feeling they will be atleast as big. But those shapes may not reflect the city as much as it influence.
The one in the screen we have is huge. You can only see a portion of it and it is incredibly deep if you look in the background and incredibly expansive if you look across and see the waterfalls in the distance with innumerable doors that could spawn large networks underground. That said, we don't even know how much of that city we have seen, we do know however that we can see rooftops in the bottom left corner so it could be imagined that there is ever more space.