This may not be a square at all - the street from which the view was taken may continue at this width, but I doubt it. The character of this area is such that it must be quite old, and streets of this width were unusual in those times, except near important buildings, which none of these are. We can thus assume that this is and was intended to be a small square.
For this purpose it functions reasonably well, although the slope is steep enough to inhibit some uses of the space, such as sidewalk cafés. (I have seen a street in Siena with a sidewalk café on a much steeper grade, but it isn't simple to arrange and is not entirely satisfactory.)
Notice the two half-houses. They share a common roof but are otherwise very different buildings.
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