[quote][b]Posted by:[/b] CamouflagedVirus hmmmm.... It sounded like a three pin locked door with the pins being about 1 and a half to 2 inches thick being turned open. The lock is old and is easily overturned so that it hits the inner locking mechanism, and then it slides open. but by the sound of the slide it is not that wide of a door, and it sounds like rock on rock instead of the screaching sound old metal would have. So it has to be a ston door with an intergrated locking metal system within it. ....and from what I had seen forerunners do not build their machines through nature like how earth does but within it...perhaps a door of the forerunners leading into a room where earths secret past of forerunner run ins? or a forerunner door leading into an epic battle makeing that suond, the sound that send shivers through your body as you replay the campaign level, because you know what is behind the door? We can only hope so.....[/quote] I thought it was stone-on-stone too at the end. But if you listen closely it's not so much of a scraping sound as much as it is a fluctuating resonance. The sound isn't a solid creak or scrape, it sounds more like an oscillating vibration from mechanical equipment (like engines/motors or even possibly gears).