I remember the day. I'd just arrived at my girlfriend's house and heard her brother shouting from the lounge. Her mom and brother were standing in front of the TV, watching the first tower billowing smoke. Then the next plane hit and we all thought it was the start of WW3.

But what actually happened?

Where did all the rubble go?

Did planes hit the buildings and did jet fuel bring them down? Or did planes hit but controlled demolition—or mini-nukes—cause the collapse? Or did no planes hit and something else bring down the towers?