Let us first consider the scale of this scene. It is extremely intimate. The street is barely wide enough to pass a wagon. The buildings are small, as are the windows. The gate is only large enough to pass a wagonload of hay. The sidewalks are no wider than required to permit someone to pass by people sitting on the benches (assuming that they are considerate enough to pull in their legs). Few of the dimensions of the area could be reduced without serious harm to its usability.
Notice that the gate is not strictly necessary to close the view at street level. The jog in the street that occurs just on the far side of the gate is sufficient to close the street-level view. Without the gate, however, the area would bleed off into the distance and lose some of its intimate quality.
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