It was about in 1975/1974, when I was 6 or 7 years old. I lived on a plain, no mountain, in the north part of China.
I can't remember the exactly day. It was at a summer noon. In those days, China was very poor, I seldom saw even an airplane.
After my grandmothers death, I did nothing outside.
Then, a feeling I had, I looked straightly up. I saw metal cube, no lights, just over my head.
A perfect cube about 3'. I think I can reach it if I jumped up. It seemed a same size of gear on the side of its bottom.
Just when I looked at it, at the same time, it flew away along the horizon, becoming a point in the far away, and disappearing, not any sound. The total process is about 1 to 3 seconds.