Building 7 No clouds of explosives seen that would have been noticed if they had been used.
The Twin Towers collapsed from the top, where they were hit, to down, not down to top which would have occurred if explosives were used. Their structures were unique and they collapsed according to how their architect said they did after the planes hit,; he should know.
In England we had a block of flats collapse down one side when a gas leak exploded a few stories up. Bad design, followed by the top floors crushing down on the ones below led to the ‘house of cards’ effect.
‘Elementary, my dear Watson’, not conspiracy!