I scarcely know how to describe that room. It became, in a way, every room I had ever been in and every room I find myself hereafter will remind me of Giovanni's room. I did not really stay there very long--we met before the spring began and I left there during the summer--but it still seems to me that I spent a lifetime there. Life in that room seemed to be occurring underwater, as I say, and it is certain that I underwent a sea change there.
To begin with, the room was not large enough for two. It looked out on a small courtyard. "Looked out" means only that the room had two windows, against which the courtyard malevolently pressed, encroaching day by day, as though it had confused itslef with a jungle. We, or rather Giovanni, kept the windows closed most of the time. He had never bought any curtains; neither did we buy any while I was in the room. To insure privacy, Giovanni had obscured the window panes with a heavy, white cleaning polish. We sometimes heard children playing outside our window, sometimes strange shapes looked against it. At such moments, Giovanni, working in the room, or lying in bed, would stiffen like a hunting dog and remain perfectly still until whatever seemed to threaten our safety had moved away.
A few paragraphs later, David thinks about why the room is so dirty and disorderly:
But it was not the room's disorder which was frightening; it was the fact that when one began searching for the key to this disorder, one realized that it was not to be found in any of the usual places. For this was not a matter of habit or circumstance or temperament; it was a matter of punishment and grief. I do not know how I knew this, but I knew it at once; perhaps I knew it because I wanted to live. And I stared at the room with the same, nervous, calculating extension of the intelligence and of all one's forces which occurs when gauging a mortal and unavoidable damger: at the silent walls of the room with its distant, archaic lovers trapped in an interminable rose gardem and the staring windows, staring like two great eyes of ice and fire, and the ceiling which lowered like those clouds out of which fiends have sometimes spoken and which obscured but failed to soften its malevolence behind the yellow light which hung like a diseased and undefinable sex in its center. Under this blunted arrow, the smashed flower of light lay the terrors which encompassed Giovanni's soul. I understood why Giovanni had wanted me and had brought me to his last retreat. I was to destroy this room and give to Giovanni a new and better life. This life could only be my own, which, in order to transform Giovanni's, must first become a part of Giovanni's room.
It is a room from which David, afraid of his own feelings for a man, escapes, in the end, only to realize that he can never escape from it, for "every room I find myself hereafter will remind me of Giovanni's room." Even sex, fleeting sex, leaves its mark, however lightly and faintly, let alone love offered and rejected.