sphere sighted at "top of the triangle" resturant in pittsburgh, pa...

we(my wife and i)were having lunch/dinner at the "top of the triangle" restaurant atop the steel building in pittsburgh pa. it was a clear, sunny afternoon and we were sitting by the window enjoying the view. we were talking and my wife (looking out the window) says what is that. i turned around and about 20 feet outside the window behind me there was a small sphere about the size of a soccer ball just hovering level with our floor. it was flat white in color. at first i thought some little kid lost a balloon, but it wasn't asending as a balloon would have been. anyway, my wife says again,,,what is that. just then it starts moving slowly right past our window, makes a 90 degree turn and flys away on a level course until it was out of sight. i tell my wife, i don't know what that was, but if someone was inside that thing they were only three inches tall!!  ha ha.  about 10 seconds after this thing was out of sight, a civilian type hellicopter flew swiftly by the building heading in the same direction as the ufo. another thing that i found strange was that the room was full of people and it didn't look like anybody else saw it. how could that be!!!  note; the date that this occured is a guess. all i know is that this happened before 1995. in 1995 we started having kids and the only resturants we went to until lately were mcdonalds , chuck e cheeses ect....