Chicago 1966 sighting when no aircraft were flying.

Craft was seen several miles away in the beginning by myself and our neighbors. My friends parents, his aunt, my mother, him and myself witnessed the event. Within a few minutes it almost flew directly over us (aprox 300 to 400 feet above us)traveling from south to north, it was between 400 and 500 hundred feet long and about 75 to 100 feet wide. What was strange is that we all watched it pass by and none of us said anything about it until it had passed. We just looked at it without saying anything until it had pasted by. The next day it was front page news of the Chicago Times, many other people saw it and called police. The commerical pilots were on strike at the time and no planes were in the air. Air force stated that they had nothing in the air over Chicago at the time of the sighting. Craft was fully illuminated all around, there was no sound and it traveled at maybe 40 to 60 miles per hour.
Date is approximate.  PD