3 AM. Delivering papers 1 block north of Fort Sheridan, off Sheridan Rd. Dark, floating, soundless UFO floats across sky.

At 3AM, about 4 yrs ago, when I was 21, I was delivering papers in Lake Forest, Illinois.  I was 1 block north of Fort Sheridan.  The sky was dimly illuminated by surrounding streetlights, etc...  I looked up, and over treetops a dark, lightless, soundless, UFO floated.  It was so low I probably could of hit it with a rock, easily.  I was excited, and decided to follow it.  I noticed it wasn't the shape of flying craft normally seen.  It was a solid shape, like rectangle, triangle, square, but I was more excited to follow it, so I didn't focus on exact shape.  It wasn't enormous, but not real small neither.  I did notice it seemed to have bumps and ridges on the bottom.  I have a sunroof, so when it flew over my car I could see it.  I chased it, but soon gave up because I couldn't maneuver the small suburban roads well enough to follow it's flight path.  It floated in a straight path, not seeming to gain altitude (very low).  It floated slowly.  I lost it in the darkness.  My assumption was it either flew directly over Fort Sheridan, or it took off from Fort Sheridan.  (Fort Sheridan, as to my knowledge, is a closed military base).
Source of report indicates that the date of the event is approximate.  PD