u/Single-Sentenc3

My office overlooks a high-rise construction site with a tower crane. While I’ve been able to learn a lot from just watching, I’m a bit puzzled by these two concrete blocks that the tower crane has been shuffling around the site.

I’ve wondered if they were some sort of concrete test, counterweights, or to test for crane capacity, but none of those seem quite right.

Any answers are appreciated - as well as any suggestions on resources that would answer the myriad of construction questions that cross my mind.