On a road in between Sonderborg and Graasten in Denmark, on the way to work at the parent Danish firm that I work for in the USA. At about 45-60 degrees from the horizon, on a very dark morning (prior to sunrise) I spotted a huge perfectly shaped rectangular object glowing with white light. It was startling since this is a rural area and their are no large buildings nor large lights of any kind even close to this area of Denmark. I pointed this object out to both the driver (a Dane) and another American in the back seat. As we continued to drive to work we all searched for expanations for what we were seeing, with no clue whatsoever. We observed this object for about 5-6 minutes at which time it seemed to collapse from both the top and bottom (long sides of the rectangle) while still maintaining a clearly defined shape, until it vanished. The Dane who was driving was just as flabergasted as we were at this sight and checked the local radio and television news shows, as well as newspapers for any reports, but their were none. We also noted at the time that the position of the moon made it impossible to make it any type of reflection or moonglow through the clouds. We also tracked the position of the moon the remainder of the week while travelling the same route to work, and each day it was not even remotely close to where we had seen this object. We were also unable to find any other witnesses to this event. We also observed what appeared to be an unusual amount of military aircraft activity in the daylight skies the remainder of the week.