Rectangular, silent craft gliding over houses about 100 feet up.

I saw a rectangular shaped object gliding slowly across the night sky about 100 feet in the air. It moved across the street above the houses. I could see a metallic base with some sort of tubing or piping.It was a dark grey colour or nearly black. It was about 60 feet in length. Something just made me look up and there it was. This is my second ufo encounter and I am really creeped out about it all. The silence of the thing is the thing that sticks in my mind. It eventually moved across the houses out of my view.
Witness indicates that date of incident is approximate.  PD