WTC was closed for "maintenance" Sept 1st & 2nd 2001. In the weeks and months following 9 11 I remember  reading about an English guy who worked in WTC who said it was strange that they closed both towers (& probably Bldg 7) just over a week before.  There was a lot more to the report but I can't remember it now, suffice to say it  raised some questions as to the timing, suggesting it was an opportune moment if anybody wanted to plant explosives there. I tried to find the report but can't find it anywhere now. The below is the only thing I could find to confirm that the maintenance closure happened. I wonder how many other related, relevant and important stories have disappeared below the radar since it happened. http://911hardfacts.com/report_09.htm