The image of the city.

1) "Looking at cities can give a special pleasure, however commonplace the sight may be. Like a piece of architecture, the city is a construction in space, but one of vast scale, a thing perceived only in the course of long spans of time. City design is therefore a temporal art, but it can rarely use the controlled and limited sequences of other temporal arts like music. On different occasions and for different people, the sequences are reversed, interrupted, abandoned, cut across. It is seen in all lights and all weathers."

2) "The image of a given physical reality may occasionally shift its type with different circumstances of viewing. Thus an exprssway may be a path for the driver, and edge for the pedestrian. Or a central area may be a district when a city is organized on a medium scale, and a node when the entire metropolitan area is considered. But the categories seem to have stability for a given observer when he is operating at a given level.
None of the element types isolated above exist in isolation in the real case. Districts are structured with nodes, defined by edges, penetrated by paths, and sprinkled with landmarks. Elements regularly overlap and pierce one another. If this analysis begins with the differentiation of the data into categories, it must end with their reintegration into the whole image."

3) "As connections multiplied, the structure tended to become rigid, parts were firmly interconnected in all dimensions; and any distortions became built in. The possessor of such a map can move much more freely, and can interconnect new points at will. As the density of the image builds up, it begins to take on the characteristics of a total field, in which interaction is possible in any direction and at any distance."

4) "We have the opportunity of forming our new city world into an imageable landscape: visible, coherent, and clear. It will require a new attitude on the part of the city dweller, and a physical reshaping of his domain into forms which entrance the eye, which organize themselves from level to level in time and space, which can stand as symbols for urban life. The present study yields some clues in this respect.
Most objects which we are accustomed to call beautiful, such as a painting or a tree, are single-purpose things, in which, through long development or the impress of one will, there is an intimate, visible linkage from fine detail to total structure. A city is a multi-purpose, shifting organization, a tent for many functions, raised by many hands and with relative speed. Complete specialization, final meshing, is improbable and undesirable. The form must be somewhat noncommittal, plastic to the purposes and perceptions of its citizens."

5) "These clues for urban design can be summarized in another way, since there are common themes that run through the whole set: the repeated references to certain general physical characteristics. These are the categories of direct interest in design, since they describe qualities that a designer may operate upon. They might be summarized as follows:
1. Singularity or figure-background clarity: sharpness of boundary; closure; contrast of surface, form, intensity, complexity, size, use, spatial location.
2. Form Simplicity: clarity and simplicity of visible form in the geometrical sense, limitation of parts (as in the clarity of a grid system, a rectangle, a dome).
3. Continuity: continuance of edge or surface; nearness of parts; repetition of rhythmic interval; similarity, analogy, or harmony of surface, form, or use.
4. Dominance: dominance of one part over others by means of size, intensity, or interest, resulting in the reading of the whole as a principle feature with an associated cluster.
5. Clarity of Joint: high visibility of joints and seams; clear relation and interconnection.
6. Directional Differentiation: asymmetries, gradients, and radial references which differentiate one end from another; or one side from another.
7. Visual Scope: qualities which increase the range and penetration of vision, either actually or symbolically.
8. Motion Awareness: the qualities which make visible to the observer, through both the visual and kinesthetic senses, his own actual or potential motion.
9. Time Series: series which are sensed over time, including simple item-by-item linkages, where one element is simply knitted into the two elements before and behind it, and also series which are truly structured in time and thus melodic in nature.
10. Names and Meanings: non-physical characteristics which may enhance the imageability of an element."