Some gaping holes in the official story would be the fact that it was the first time in history that 2 steel structures fell at the rate of free-fall due to a fire (meaning no resistance) and a third, 47-story building which no airplane hit, also fell that day. http://rememberbuilding7.org/
The twin towers did not come down at free-fall speed, this simply is not true. Loose sections of the facade fell near free-fall speed (air resistance slowing them down a bit), but there were internal columns collapsing significantly slower, indicating that there was indeed resistance to the collapse.
Steel gets soft when heated, at temperatures far below the melting point. All blacksmithing depend on it - put steel in a fire for a while, bang on it with a hammer while it's hot and malleable and it alters shape readily. Similarly, loaded support columns will buckle and bolts will shear off at forces far below their rated strength if they are heated by fire.
The building collapses on 9/11 (including building 7, damaged by debris impacts and on fire for several hours) were unique events in scale but not in principle, as there are plenty of precedents of steel structures collapsing from prolonged fires.