The apartment, a unit in a 21 years old residential building sitting at the central section of Chongqing City, China. The building constructed on the mountain, respecting the original landform, is a typical precious local residence. It used to be the home of a couple with their only child in the past two decades. It is now owned by a young couple. Dissatisfied with the original layout, lighting and ventilation, the young couple wishes to have the apartment reconstructed so that it is to become more pleasant, comfortable and functional to meet their needs.