I almost collapsed that wood sidewalk shed by accident when a huge chunk of cornice stone fell off the top of the wall while I was prying on a keystone nearby, the stone landed on the scaffold about 10 feet below which then started to sway out towards the street!

You can see where the stone was in the bottom photo, in the center of it over a large white square panel with a shield in the center of it, to the left over the blue doors you can see what the rest of it looked like (though that was smaller) and how much fell down.

The first photo shows what fell down a little better, it was a projecting cornice with 6-8 corbels under it, all limestone and heavy.

One of the holes over the windows to the right was where I was working and I jiggled the brick wall just enough with my crowbar to topple that stone a few feet away, so it was not very stable or secure when the workers left for the day if that's all it took.