Roderick Usher, the proprietor of the house of Usher, is a metaphor of his surroundings in as much as the surroundings are a metaphor of himself.
The narrator describes the room as follows:
The room in which I found myself was very large and lofty. The windows were long, narrow, and pointed, and at so vast a distance from the black oaken floor as to be altogether inaccessible from within. Feeble gleams of encrimsoned light made their way through the trellissed panes, and served to render sufficiently distinct the more prominent objects around ; the eye, however, struggled in vain to reach the remoter angles of the chamber, or the recesses of the vaulted and fretted ceiling. Dark draperies hung upon the walls. The general furniture was profuse, comfortless, antique, and tattered. Many books and musical instruments lay scattered about, but failed to give any vitality to the scene. I felt that I breathed an atmosphere of sorrow. An air of stern, deep, and irredeemable gloom hung over and pervaded all.
The importance of this description rests on the adjectives used by the narrator to convey his personal feelings. Words such as "inaccessible", "feeble", "sorrow", "stern", "pervasive" and "irredeemable gloom."
Those are all words that convey the tone and message that the narrator is trying to explain: Usher, in his deterioration, as fallen under all these descriptors: He was indeed a man who has become feeble, with a pervasive gloom of character, and whose psyche is inaccessible to the common man as he suffers from something that comes from a source higher than any of us, as if in the shape of a curse.
Therefore, the room of the house conveys a sensation of terrible anxiety and awful sorrow that is the embodiment of its proprietor and his fallen clan.