I was not aware that they stored anything but paperwork at Iron Mountain, but it makes sense. Iron Mountain is likely the largest of many such facilities best known for records storage and management. When referring to materials sent to a storage location, many bankers and business people will say they're in "the warehouse". The trucks of these companies can be seen on NYC streets daily, both picking up and delivering files and other records in boxes and envelopes. It's hardly a "conspiracy" for the government to use one for the safekeeping of 9/11 articles.