Close encounters of the real kind (space craft) for at least one minute about 100 yards right over my head

I was 11 years old on this one particular bright day in the afternoon in the summer of 1974 when I was standing outside my two story duplex house when a cast of dark shadow cover me and the whole house.   When I looked up there was this huge aircraft flying right over my house traveling less than 5 miles an hour.  
I fell to the ground frightened by the size and how low it was traveling.  At this particular age I was not sure what to think this really was.  This aircraft made no noise whats so ever.  It just came up behind me out of no where.  
I would say that this aircraft with its technology probably took pictures of me hundred times before I noticed its existence.  
The other side of my block is about 100 ft. across approximately which at the speed of this aircraft was traveling, they had observed my presence for at least 30 seconds or more before I identified them.  There are houses on the other side of my block.  
When I fell to the ground I was looking at this aircraft slowly flying right over my two story house with cavities and lights underneath its craft and dark greyish in color.  Iam not exactly sure the total shape of this aircraft because it was so low hovering right over my head.  
When it passed my house I could not believe what just happen.  
I ran up my house and told my parents but there could not understand or comprehend my story.
Witness indicates that the date of the event is approximate.  PD