If the WTC Towers Were Brought Down by Explosives, How Was It Done?

Related question: if the Twin Towers were brought down by demolitions, why didn't they come down like WTC7, which looked very much like a traditional controlled demolition? The answer to this question is that WTC1 and WTC2, the Twin Towers, were of course built very differently from WTC7. WTC1 and WTC2 were massive, incredibly large structures that had a very different type of design than WTC7, which was more of a traditional skyscraper design.

How then, were the Towers brought down?

While there is evidence of bombs on upper floors of the WTC (also here), it is far from clear that these would be enough to bring the towers down by themselves.

Explosives on the upper floors coupled with severe damage to the foundations might well be enough to bring down the Twin Towers in the manner they were observed to fall. Controlled demolitions typically involve blowing the foundations. There are three pieces of evidence that point to the foundations of the WTC being blown:
1) the presence of incredible heat in the rubble of the WTC towers and the presence of molten steel in the basement areas after the rubble was cleared.
2) seismic shocks that registered before large pieces of the towers started hitting the ground.
3) Eye-witness testimony of bomb damage in the WTC basement.

Evidence that the core of the North towers was blown and was collapsing before the floors started collapsing is shown by videos which show the roof antenna of the North tower falling straight down before the rest of the tower comes down. (This last video also shows some interesting vibrations shortly before the tower comes down.)

Overall, the evidence fits with a combination of explosives in the upper towers as well as in the basement, blowing the foundations, that caused the towers to collapse the way they did.

Although we can't really rule out other more bizarre ways the towers were destroyed, such as by microwave energy-type weapons or radiant energy projectiles.