WTC buildings, signature demolitions. News reports first stated so (they didn't get the script).

Demolition of the Twin Towers at near free-fall speed

The government’s official explanation is that the combined effects of airplane impact damage, widespread fireproofing dislodgment, and the fires that ensued created a pancake collapse.

Their investigation “found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to September 11, 2001.”

Watch these clips. Do you still believe that fire caused the towers’ collapse?
Thermite burns at higher temps, than standard fire. Why do you think the steel, everything was still burning for days?
Thermite and C4 brought all buildings down.