Here we have a typical Parisian boulevard. It is a lesser boulevard, as can be noted by the absence of the service roadways and its comparatively narrow width. It is, in fact, narrow enough that it integrates nicely - there is no sense of "the far side of the street." One can take in the full view.
As is usual, it forms a retail center, with shops lining both sides of the street. In medieval design, commercial spaces are concentrated around (and within) squares, with the result that these squares are usually the scene of bustling activity. They often host markets, a function not well served by the boulevard. It is important to keep in mind that a city can have only so much open public space; if there is too much, there is not enough pedestrian traffic to make the area come alive. Narrow medieval streets rarely suffer from this problem, but it can easily afflict a city of boulevards, unless the density of construction is quite high (i.e., using fairly tall buildings and very small interior courtyards).
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