55strict views and movement via canalization through inter-
mediate spaces. The spaces of streets and public > squares,
finally, are contained by the closed fronts of buildings. Through
a bend in the front level or a broken sight line in elevation,
the street space closes itself off to perception longitudinally as
well. The gaps in the corners of a public square seem closed
when the streets flowing into it are arranged like the vanes of
a windmill, blocking views to the outside (Sitte 1889/1983,
40f). If, however, the fronts of the square are open instead,
a certain closure is nonetheless effected through the overall
figure, since perceptual operations supplement it, filling in the
missing fragments of the contour to form a complete > gestalt.
In extreme instances, four corner houses suffice to produce
the impression of a rectangular square. Chamfering the cor-
ners – an example being the Quadrivio delle Quattro Fontane
in Rome – gives the figure a certain > concavity, contributing
to a sense of closure.
The degree to which a square appears closed, meanwhile,
is highly dependent upon the proportions between its overall
surface and the height of the building fronts that contain it.
When the head is held stationary, the > gaze as a rule takes
in only a limited visual field. As a rule, the gaze reaches only
up to the height that allows us to view the building fronts up
to the level of the cornices when we gaze across a square that
is twice the width of the building heights. Then the space of
the square seems quite closed. If the width is three times the
heights of the building fronts, a large section of the sky enters
the picture, and the square begins to open up, yet still without
losing its compactness. When the distance between buildings
is between two and three times the average building height, an
impression of closure and modest expanse prevails (Maertens
1877). Should the intervals between the containing buildings
become too large, they no longer guarantee the cohesion of
the figure of the square, and a sense of closure is sacrificed.
If it is to play off the contrast between a restrained outer
appearance and the elaboration of the interior space within,