What Caused Building 7's Collapse?

Building 7 was 5 times as tall as deep.

To bring this building down into its footprint required that all 58 perimeter columns and 25 core columns be destroyed simultaneously.

Any asymmetry in damage would cause asymmetric collapse:
the building would topple.

No combination of rubble impact damage, fires, or fuel tank explosions could have destroyed all columns simultaneously, as required to cause a vertical collapse.

Only controlled demolitions have achieved vertical collapses of upright steel structures.