Additional reporting from Denver Gazette.
Reddit user Lemonator8976 claims to be the witness that reported the sighting and provided some additional details.
The follow up article explains it, but basically we were working. We were loading semis full of expensive concert equipment and then one guy noticed it and pointed it out. We all looked at it and then one guy shined his flashlight on it. Then the thing tipped, moved slowly to the east and disappeared. By the time we realized what was really happening it was gone. 30 seconds max.
A big misconception is that this thing was way up in the sky. It wasn’t. It was hovering over the hill not very high off the ground. It was just off the horizon, not way up above our heads. An old boycott trick is to hold your hand up to the horizon to see how many hand lengths you have left before the sun sets. This thing was just two fingers above the horizon.
Couldn’t see any other features. It was too far away and it was matte black. Like the blackest black you’ve ever seen. The black blended in with the night sky so well, we probably wouldn’t have seen it if it didn’t have its lights on.
The lights were around the edge rim of the disc. They were evenly spaced apart and you could see them curve around the to backside of the disc.
I was not wearing my glasses and I have an astigmatism, so I could not make out the windows. All I could see was the disc and the lights going around it. It was my a couple of my coworkers who said they could see the windows. They said it was like a grid that was 3 squares high several dozen squares long all the way around the craft. The thing was a couple blocks long, hence why I described it as a “3 story office building in the sky”. It really was that big.