I was visiting a friend in north west edmonton. at exactly 11:45pm i went on the balcony for air. it was a clear night sky. i heard a noise behind and above me as i was sitting in a chair. at first i believed it was a helicopter but i did not see any lights on it. then i heard what sounded like a rumbling engine of a large loud diesel truck. i looked and did not see a truck anywhere on the roads. it wobbled unsteady a little and went slowly in a straight path and the sound was coming from the sky. i looked above me and it was hoovering. at a second look i realized that the noise was coming from the object. i examined it for at least a good 3 minutes before i lost site of it behind a tree. it was a complete rectangle with no lights. i could clearly see it and details of it as the stars and moon reflected off of it and it was moving very slowly. i could not get over how loud it was. i was too mesmerized to find my phone as a guest. it appeared to have patchy metal pieces, not smooth, maybe even dented up. rough looking. i did not observe any windows either. it was very loud like a big clunky diesel engine in the sky. it went very very slow and had clear outlines. and then it disappeared behind a tree and so did the noise. the only thing i noticed is that ear ringing has not given up since i witnessed this.