It was around 1.40 at night Friday 14th of March 2014 when I heard a sound from outside of my flat. In the beginning I thought it was a car waiting with the engine turned on. After a while it started getting distant but not disappearing. I opened one window to see who it is but no car outside. It was a noise like a big vibrating roar. I thought it might be the central heating of the building but immediately I realized it was coming from the top of the next building. Like it was hovering above it. Then it started moving around, at that point I realized that something is not quite right. I couldn't see anything. The night was not a dark night, I could clearly distinguish the horizon over the hilltop nearby and the lights of the area was helping to that as well. Then it hovered around the area for a little while and after it started going away. At this point I could clearly hear its direction and estimate its position by its sound but I could see nothing. It went quite far and stayed for some time at that distance. Then it started coming back and I closed the window because I was afraid. But after a while I opened again the other window of my flat and I heard it hovering slowly around and stopped above a school football field just outside my building. It stayed there for a few minutes and then started coming towards my direction. I was scared but I tried to stay at my window. I couldn't see anything all this time but I could hear it very distinctly. It came towards my direction and passed right above my building, I even bent over the window as it was passing over the building just in case I see something, but I couldn't see anything. It sounded like it was something big, there is no way something of that size to come so close and I couldn't see it. At that moment I heard its sound better than any other moment, it was like a fast roar and when closer it had a vibrating feel and a slight metallic sound to it. At that point I got scared and I closed the window. I could hear it being out there for another 15 minutes and then it went away. When after 1 hour or so I opened the window, it was dead silent outside. I even thought the possibility that it was only my idea to hear the sound but the fact that when I closed the window the sound was damped, it was indicating that it was outside.Also I don't know if that is connected somehow to that object but the following morning at 8.30 when I went to work, the company next to the one I work had smoke next to it and the workers where running around like they wanted to distinguish a fire. I really believe that these two events are not connected to each other but I thought to mention this last one too, just in case it helps any research.I know my data are not sufficient to really identify the object because I couldn't see anything really, but I thought to submit my experience just in case there is any other witness from that event from the nearby area. I really didn't think to take my camera and film the situation because I was scared at that moment.