Two publications that have greatly influenced me in recent years are Made in Tokyo by Atelier Bow-Wow and Informal China, a special issue of Urban China Magazine (Issue 9, May 2006) edited by Jiang Jun. Both richly illustrated publications offer a conceptual dictionary for reading the city.  In Informal China Jiang Jun has brought together a fascinating collection of images from across China documenting structures that were grafted on existing structures to meet a new functional need.

As Jiang Jun writes: "In [the] Informal City, all spaces are instinctively changed into (the) construction sites. Under the limitation of policy, economy and technology, the sites are differentiated into 'possible sites' and 'impossibe sites'; (the) space construction in the former sites is usually legal and regular, while that in the latter is illegal, irregular or even incredible."

Another category introduced by Jiang Jun is that of 'Impropriated sites'. In the words of Jiang Jun: "Although predefined with a certain function, a site can generate other content with its own particular context, moving away from being just a piece of land. The predefined function disappears when some factors are wrong, or go beyond the tolerance in either the context or the content. Thereafter the site may be left unused or temporary dead until becoming an Impropriated Site." Thus dry riverbeds can become cropland or make-shift markets, pools where rainwater has collected can become the basin for a goldfish salesman.

One of the most visibly striking features of Chinese, and indeed Asian cities in general, is the commercialization of the street level. As Jiang Jun writes: "Ground floor originally is the basic layout of high buildings. However, it is auto-commercialized as submerged by even bigger public space or consumer crowd. Pushing down walls and opening new stores are the direct result when the Ground floor in a non-commercial building is commercialized. In architecture, this inner explosion usually starts from openings (doors or windows), through improving its accessibility, as well as increasing its openings, intensifying its visibility to the point when 'Staff Only' is replaced by 'You Are Welcome'."

As an extension of this phenomenon, alleys and corridors are turned into restaurants. And since the number of businesses exceeds the amount of available space on street level, hair stylists, massage parlors, financial service providers etc. open up shop on higher floors and try to attract customers with billboards, neon signs and other forms of signage hanging from flagpoles or decorating the wall or window. Thus private, public and commercial space are no longer clearly defined.

Through stacking, enveloping, patching and recycling buildings grow like an organism. Balconies are enveloped, patios are roofed and interiors are expanded through make-shift add-ons. As Jiang Jun writes: "Originally roof acclaims the end of architecture at top. But now, it predicts a beginning of another construction, as well as another free site in Informal City. The top units have the priority to develop roof site. They take the advantage of being top, and grab this untitled land to be private property in the form of Expanding Interior."

However, such roof structures are not without hazard. When entire floors are stacked onto existing floors the building may become unstable and may even collapse, as occasionally happens in cities such as Cairo and Caracas. Temporary, light structures, made of bamboo and plastic may be blown away during the next typhoon, as they do in Hong Kong and other coastal cities in South-China.

As Jiang Jun observes: "In [the] Informal City, rigid and fixed structure is always ephemeral, whereas dynamic, adaptive and repeatable structure is (every) durable." The Informal City is therefore governed by an inverse logic of the fixed and the ephemeral. Rigid structures are temporary and can be replaced at any time, whereas ephemeral structures are permanent, not in terms of site or structure, but as building types that pop up everywhere and at any time.