We saw a huge diamond shaped object hovering over us.It was a Monday evening in October of 1996, I'm unsure of the exact date. My mother(a complete non-believer) and I were traveling east on a major street in town when we saw just ahead, a little beyond the next intersection what looked like several helicopters flying very low, coming toward us. We discussed the flying machines and decided the white lights which were strobing were much too bright for helicopters. Just then, two blocks past the intersection, we were right under it. I turned on the side street and we got out of the car. The diamond or square shaped as we decided object was just hovering in the sky with no noise. With every observation I made I asked mother if she agreed and she did. This thing was huge approximately 600 feet in all directions. We were underneath and could see the apparent color charcoal. We estimated it was no more than 100 feet above the ground and the lights were at the corners. We could also see individual squares marked off on the underneath side with carvings or writings of some kind we could not identify. Some time later I saw a celtic cross and thought the artwork was the same or very similar. We just stood under it discussing it, mesmerized. Mainly we talked about its size. A few minutes into it we saw and heard a jet coming down the same main street toward us. At almost the same time we spotted the jet, the big craft took off in a northwesterly direction being chased by the jet. I don't know why but we still stood there watching until they were almost out of sight unable to move. Finally we jumped in the car and gave chase but never saw either again.