Sunday afternoon, Brussels: containers are in the air…
My interpretation would be that there is something valuable or important in the container which has (you can’t see it on the picture) wheels. So probably the construction workers were afraid that someone could have the idea to take what is inside the container or, why not, the container itself. And since there is no place to close it away, they choose the safest place they could find and left it there for the weekend… Still, looks strange.