Football sized saucer over Hagertown MD in summer of 1974

It was dark out, and my wife and I just got out of our car close to our apartment on West Franklin St. For some strange reason we both looked toward the downtown area in the sky. Above the square of Hagerstown was a craft that seemed to be about a football field long, and was hovering silently. My wife and I just kept looking at it without even saying anything for awhile. It had different colored lights slowly revolving around it's perimeter. We couldn't believe the size of it, plus the fact of no noise. Then we began to talk about it, watching it slowly begin to move to the west.All at once it sped up to an incredible speed and vanished. I went to the apt. and called Hagerstown Airport and asked if they picked up anything on radar,and they said no. We have kept quiet about this forever. Now we aren't exactly positive of the exact date that summer, since it has been such a long time, but we will remember this the rest of our lives. The reason I am doing this now is, we are wondering if anyone other than us had seen it.
Date is approximate.  PD