A family member had called to me while busy doing high school homework to come and see a "UFO". I had read books(Is Something Up There? and other works)about UFO's and did believe in extra terrestrials and their crafts. That night I initially did NOT believe this family member because we were in Harlem, N.Y. and I firmly believed that no UFO would be in Harlem and that if anything they would appear over a mountainous region where the population was not heavy and near secluded power lines(electricity and magnetic forces). So I ignored the prompts to come see this object believing the family member was playing a joke. The family member began begging me to please come ans see this "UFO" as he called it. In Harlem!! I thought again. I refused to look. The family member then frantically called to another family member to please come see the "UFO". The other family member went to the window where the first family member was seated and locked their eyes on "something". I observed both of them from the living-room couch I was on and observed both were VERY fixated on "something". I asked the second family member "Is there a UFO out there?" The second member remained very fixated on whatever they were watching and only nodded in the affirmative to me but never looked at me and remained staring at whatever was in view. So, I said to myself they are both in on some type of joke on me but this was never a concerted prank before. So, I decided to play along and got up to see for myself. I looked out of the window nearest to me to their left. I observed a circular greyish metallic object turning as it moved. It was moving from North to South approximately 30 to 50 feet in diameter and 20 to 30 feet in height. This object was only approximately 100 feet or less from my position and our top floor window was on the fifth floor of our tenement building. The object was no more than 20 feet above the rooftops across the street. This object, once I observed it, made a straight line reverse after passing a few feet past the window. Still turning as it moved(went). This reverse action was VERY SMOOTH!!! It then stopped and hovered directly opposite me while still turning. The turning motion was NOT in a complete circle. I was a Math and Science student and clearly observed a total turning motion of approximately 315 degrees. The two family members had now ran over to the window which I was at and began to ask me if I now believed them. I was so shocked but amazed I firmly told them to be quiet to hear from the already opened window. I immediately while observing the odd non complete circular rotations while it was hovering that there was NO SOUND being made by this craft. While it was rotating, I tried peering into the four to five fluorescent like window panes. I could not see anything but the bright white light from the panes. These windows helped me gauge the turning(rotating) distances. Since we were on the top floor I immediately said to my family members to let's run up to the roof for a closer look. While running to the apartment door and then to the roof door(which took less than 10 seconds), I was scared but so amazed that I just had to have a closer look at this amazing silent aircraft. Upon opening the roof door the craft would have been directly opposite the roof door but was now nowhere in our immediate view. When we searched the sky we observed a slightly tilted object rotating with windows passing the midtown area of Manhattan at least five miles away. This may or may not have been the object we had just seen but I would say that with a very high probability it was the same craft. The first family member asked should we report this siting to the police or news. I quickly told the family member NO because no one would ever believe that a UFO was in Harlem and we would be laughing stocks or labelled crazy/lunatics. The first family member had told me he waited before calling this object a UFO because blimps also moved smoothly and slow turns but observed that this object did NOT turn to reverse but made a straight line reverse which was observed multiple times over at least a ten minute period which then prompted them to call me to see it and to verify his sighting. After recently visiting the Kennedy Space Center I would best describe this craft as an over-sized space capsule that can hover and rotate at the same time.