In "The Masque of the Red Death", what chamber is not occupied by the masqueraders and why?

It is important to realise how Poe uses setting
symbolically in this great story. Remember the scene - Prospero has locked himself and
his revellers in a castle in an attempt to cheat death as the mysterious disease, the
Red Death, runs amok outside in the Kingdom killing all in its path. This scenario could
be viewed symbolically as someone trying to cheat death and outrun it, ignoring death's
dominion over human life.

The masque ball therefore is very
significant in terms of its setting. The last, seventh room, is the one where none of
the people wish to enter. Note how it is described:

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The panes here were scarlet - a deep blood
colour... in the western or black chamber the effect of the firelight that streamed upon
the dark hanging through the blood-tinted panes, was ghastly in the extreme, and
produced so wild a look upon the countenances of those who entered, that there were few
of the company bold enough to set foot within its precincts at
all.

Note too that in this
suite there is a massive ebony clock. Clearly this is symbolic of the passing of time
and the approaching death of all the guests. The fact that this black room is the most
western, at the rooms run from east to west also indicates the passing of time and the
approaching death, as the sun rises in the east and goes down in the
west.

These guests are engaged in a quest to try and cheat
death and forget about it, therefore it is highly significant that they do not want to
enter this room, which could be said to symbolise death, with the ghastly red light
signifying the Red Death that is about to come upon them all. Also note that it is in
this room that the masked uninvited guest confronts Prospero and death is admitted into
the castle.