I used to walk past the Minneapolis Public Library twice a day. Now it’s a pile of rubble with one remaining shell that will probably be gone in days. They’re tearing down the old building to put in some new fancy one.
I’ve been able to watch the progress as they go. They spent a lot of time inside the building, ripping everything out. I watched one day as a Bobcat shattered every window on the third floor and then ripped out the window frame. The claw on the end of the Bobcat’s arm would stab through the glass, then turn to rip out the frame. The glass would bubble and then pop when pressure was applied, usually sending most of the shards shattering to the ground. But the claw never hesitated. As soon as it broke through the glass it was reaching around to grab the frame, yank it out, letting any remaining glass fall to the ground. The Bobcat was in position for the next window before the sound of broken glass silenced.
A crane with a large concrete ball toppled most of the building. The concrete ball was probably twice the size of a basketball. A chain went through the ball going up to the crane, and another chain fell below the ball, and then curved back to the crane, allowing them to both drop and swing the concrete ball. A slow, simple swing or drop is what brought down most of the building. They’d raise up the ball, then let it fall, slowly at first, building up speed just before it smashed into the concrete. Most of the time nothing would happen. It would echo, the dust would rise, and a few pieces would fall. But every few swings a large chunk would fall, and a piece of the building would cave away. Often they would just drop the ball in a line, and then swing the ball into the weakened structure, letting an entire section of wall fall away. I watched this happen twice, seeing a 10 foot by 10 foot piece of sheet metal fall six stories.
The most amazing to watch was the dome of the Astronomy wing. They raised the concrete ball and let it fall in the center of the dome. The building shook and the ball bounced, sending reverberations up and down the chain. They raised the ball again and dropped it. Raised it again and dropped it. Again and dropped. Again. I never saw the dome give way.