Each building has its own city, but each city does not belong to only that building.
So, when Baicheng said to Ye Xiaolou, Xiaolou, I am your city, my city for life.
Ye Xiaolou just shook his head and said, Baicheng, your city is too big for a small building, so I, Ye Xiaolou, can't afford it.
Everyone will experience many cities in his life, and the one he chooses in the end is often not his favorite city, but the most suitable city.
Everyone's heart is like a city, empty for those you love.
You have been here and my memories are full, but when you are gone, my heart is empty.