It is key to realise that each of the seven chambers and the way that they are positioned running from east to west, to correspond with the rising and setting of the sun, allegorically suggests the different stages of man's life as he is born and starts his inexorable trek towards death. Let us consider how the final seventh chamber is described so we can establish its allegorical significance:
The seventh apartment was closely shrouded in black velvet tapestries that hung all over the ceiling and down the walls, falling in heavy folds upon a carpet of the same material and hue. But in this chamber only, the colour of the windows failed to correspond with the decorations. The panes here were scarlet--a deep blood colour.
Also important to consider when trying to work out the allegorical significance of this room is what happens here. Let us remember that the guest disguised as the Red Death walks through all of teh chambers before finally confronting the enraged Prince Prospero in this seventh chamber, where the arrival of the Red Death is discovered and greeted with intense dismay. The combination of the black of the trappings of this room and the red of the windows strongly points us towards this seventh room allegorically representing death, and death at the hands of the Red Death.
As was mentioned in the previous post, the seventh room in Prince Prospero's abbey represents death and decay. The seven color-coded rooms in Prince Prospero's abbey symbolize the progression of life. The first room is colored blue and represents birth. The last three rooms are decorated in white, violet, and black/scarlet. Chronically, these rooms symbolize old age (white), impending death (violet), and death itself (black/scarlet). The seventh room is located to the far west side of the abbey and is described as being an ominous black chamber that the guests avoid during the masquerade. The seventh room also has blood-tinted window panes which add to the ghastly, eerie atmosphere inside the chamber. The color black is associated with death, and scarlet represents the tainted blood that is associated with the Red Death. There is also a tall, ebony clock located in the room with a swinging pendulum, which counts down to the end of the day. The clock symbolically represents the inevitability of death as it steadily approaches midnight. In addition, the seventh room is the chamber that Prince Prospero chases the Red Death into and is eventually killed inside along with the other guests.