In modern high-rise residential complexes, public staircases are fully enclosed by walls, but that was not the case in some residential buildings in previous decades. In the tong laus of our No. 618 Shanghai Street Project, public staircases had wooden windows facing the street. The windows allowed natural light into the staircases and ventilation. The design of windows with frosted glass offered a higher degree of privacy. When our conservation team found that the windows were still in good condition, they decided to restore them and reuse them on the second floor to allow visitors to see the original window design.