Saw a very high, black louvred rectangular object headed from S to N at cloud level, over South Knox County.

I was about to start sunbathing.  Temp was about 87, partly cloudy day in South end of Knox County.  As I noticed a huge high cloud came across the sun, my eyes focused on something rectangular shaped, at the edge of the cloud height.
The object appeared to have a louvred appearance, much like that of a laundry room door or the kind of windows one sees on older homes in a beach area--louvred.  The object appeared to be black, and was headed due North in direction.  It wasn't blown on the wind, in a "wafting" type direction, it was on a steady path.  No variation in its path, as I said, just at the edge of the lower level of a white cloud and at that height, it would've had to have been easily 50x100 ft, but looked really tiny from the ground.  To place perspective, when we see a jumbo jet pass near a cloud, it looks like a period on a huge paper.  This object had to be approximately the same dimension, as it was cloud level, just under a huge cloud blocking the sun, had louvres, and was black.
I could see that half the louvres went in one direction, the other half in the opposite direction. Very perplexing, and moving quickly.  I couldn't begin to estimate speed, but I know it was definitely going pretty fast, kept its height (no sinking) and kept going due North.  It came from the direction of Maryville and crossed the sky heading toward the NE side of Knoxville City, across the sky.
I've never seen anything I could compare it to, except one of those old louvred type doors with horizontal slats running back and forth across the height of the door...matter of fact, that was my first thought when I looked up and focused on it.
There's an air-base in Maryville, approx 15 miles from here as a bird flies, but there's no way anything could gain that altitude from lifting off there.  There's an AirForce base there, too.
((ADDENDUM FROM WITNESS))
Ah! Sorry, it was absolutely Aug 10th.  I wonder if it could've been some type of low satellite or drone, perhaps?  Maybe something from Google maps...?  Perplexing.
If you do find out anything, or hear of similar reports, keep in contact.  Thanks much!
((END ADDENDUM))