During three weeks of fighting in Fallujah, U.S. troops had to deal with 653 roadside bombs (IEDs, Improvised Explosive Devices.) In the previous four months, an average of 772 IEDs were encountered per month throughout all of Iraq. The source of the large number of IEDs in Fallujah was soon found. There were eleven IED factories in the city, plus 203 weapons and ammo storage areas where raw materials for IEDs could be obtained. The city covers about twenty square kilometers, and is divided by roads into about a thousand blocks. One in five of these blocks contained one of these weapons storage areas. In some neighborhoods, every block had a stockpile of weapons. And many of these stockpiles contained several tons of material. Many (60) of the hundred mosques in the city were used as weapons storage areas, or provided firing positions for hostile gunmen.  Cemeteries, hospitals and schools were also used for weapons storage and for fighting positions. Fallujah apparently served as a major source of weapons, IEDs and training for anti-government forces throughout central Iraq.  While it appears that Fallujah was the major source of IEDs in Iraq,  most of the men who built the IEDs have apparently fled Fallujah. So these IED workshops will probably be re-established elsewhere in the Sunni Arab areas of central Iraq. However, they will have to be well hidden, and will be subject to discovery and raids, unlike in Fallujah, before the government and coalition forces moved in.