Appeared to be a formation of sorts at first; 1500-2500' feet off the surface; 1/2-3/4 mile in length E-W, 1/4 mile wide N-S; over Lake Ponchatrain,LA;Driving from New Orleans I saw what I thought was a helicopter squadron flying in a rectangular formation (6 lights) over Lake Ponchatrain. I noticed this because it looked very uniform and clean (like precision flying). As I approached, driving from W to E, I rolled down my window to look closer at this very cool sight. As I approached the leading edge of the 'formation'(a very clear night), I looked up and saw nothing but the point of light, as I continued driving, I remember how clear the stars were. As I past the last series of light on the Eastern edge, I remember thinking how odd that there was no sound, and that I couldnt see the 'helicopters' just the lights. As I drove I looked back several times to see that it had not moved. It was perfectly suspended from beggining to end 1500-2500' off the surface. A perfect rectangle 1/2 to 3/4 mile E-W long, 1/4 mile N-S wide. If you have ever driven the bridge from New Orleans East across the Lake to Slidell, the object started about just where ... if you look left you can see the train tressel, beyond that basically going E, and extended up to the area before you ascend the large hill of the bridge. Any way thats it...The odd thing, I didnt think about what had occured until I was into Mississippi, then I realized I saw something and that ... well I dont know what I saw. I wasn't scared ... But like an event where an innocent curiosity takes place you act natural, unsuspecting, non biased, moronic even. Then you talk about it the same way. It looked like a grid, a guide or a reference of some sort.... It was perfectly rectangle, very big, clear, and low! I have never seen another thing before or since.