149Two features are characteristic of the hall: first, it is the quin-
tessence of the large room, and as a rule possesses a certain
breadth; even an extended covered promenade must be more
than a simple corridor. And second, it is a room that typically,
if not necessarily, forms an independent building, perhaps ac-
companied by a few ancillary rooms.
Both features together recommend the hall for public,
urban functions. In many cases, it has large openings, and in
some, no walls at all. The decisive aspect, then, is the roof,
which – given its considerable size – must either span a large
space, or else rest on supports. In the first instance, the space
offers great freedom of movement and flexibility of use. In the
second, the supports – often in great numbers – guide move-
ment through the hall in a variety of ways, thereby endowing
it with its special > rhythm. In elongated covered promenades
such as the stoa of antiquity or the drinking halls of health
spas, the mode of movement is oriented – even when entrance
is possible from all sides – to striding up and down, and hence
to a > figure of movement that is conducive to conversation or
contemplation.
Non-public functional halls in particular, including hang-
ars, factory buildings and warehouses, must struggle with
the architectural challenges involved in covering enormous,
amorphous volumes. Through an optimized relationship be-
tween spatial height and ground area or a specific articulation
of roof and ceiling, it is possible to avoid allowing a support-
free hall to appear as an unstructured, balloon-style container.
The large volumes contained by halls, meanwhile, can be ex-
ploited in order to make palpable a liberating sense of breadth.
Such an impression is dynamized by the wide-span, often can-
tilevered roof, the rhythmicization effected through vaulting
or ceiling panels, and perhaps also by audible reverberations.
In a hall resting on > columns or pillars, the number, form and
arrangement of the supports give the space structure, while
movement is guided by the resultant zones, tracks or naves.
Beyond a certain > density, columns and pillars act as obsta-Hall