I was just about to go to bed and had already turned the lights off when I suddenly heard a noise comming from my living room next door.The door to the living room and all the windows where open because it was a hot summer day and my apartment is below a roof on the 3rd floor. I was not able to identify the sound this object made.I never heard it before or again after that day.But I could roughly say that it almost sounded like a puring cat (a very large cat)but different.More metalic sounding and loud.Almost in the same moment I heard this sound I felt all the hair on my neck and back stand up.I was so afraid that I was almost unable to move. I heard how this object was moving through the room along the walls in a circle and it stopped for a while infront of the bedroom door where I was.I was so afraid that it would come into the bedroom that I pulled the blanket over my head like a child. After a few minutes it suddenly left through the window. I told this only to a few friends and I think most didnt believe me or they thought I had too many beers that day. After that day I have witnessed 2 more UFOs.One in Germany in 1995 and another in California 2004 (I will report this too) Sorry for my poor english.I grew up in germany and live here again now.