798 is a famous art district in Beijing developed from a deserted industrial area. The drawing takes an engineering style in terms of visual language, but what it tries to express in the content is not limited to the architecture itself, but also includes the urban life in and outside the architecture. So besides the large-scale elements like buildings, roads, squares, greenery, and pipelines, the viewers can also find furniture, mechanical equipments, plantations, billboards, displays, and even tableware in the restaurants. The purpose of such documentation is to reflect the complexity and diversity of urban life through an objective recording process without missing the smallest details. In principle, the approach of creating this piece is to be elaborate rather than general, and to stay close rather than keep distance. What is interesting about 798 and the Building 42 depicted in San Li Tun lies in the fact that the buildings have gained a re-birth with new functions evolved naturally after a long-time use with their original functions. And these new functions didn’t take away the original ones and the two stay rather in harmony. This gives those architectures more significance and indications, which is much more interesting than those official transformation or conservation for old architecture. The old factories in 798 and apartment building in San Li Tun indicate a cleverer strategy to protect the old architecture and district. As being preserved and protected, the old neighborhoods obtained a true sense of contemporary but not pretentious nostalgia. Rem Koolhaas in recent years came back to the subject of preservation after years of challenging and subverting contemporary architecture. Once he commented, “I like preservation more when it is completely spontaneous and accidental”. Then it might be reasonable to assume that factories in 798 and apartment building in San Li Tun shall be something of his interest.