Thermite: How/When did they get it in the buildings w/o anyone noticing?

I did an ATS search an couldn't find a previous thread discussing exactly how the explosives were placed into the towers and building 7. Apologies if this has been discussed previous.

My recollection is that there was a security sweep and power outing in one or more of the buildings 2 weeks prior to the attack, which would explain any eye-witness accounts of security persons going into the buildings.

...but you'd have to carry a LOT of thermite with you. How did they get it in without anyone noticing?

Theories?

Existing thread: www.abovetopsecret.com...

Peace