Then it's the central pillar for a specialised crane carrying a concrete pump and an extensible hydraulic arm (instead of the usual jib) supporting the pipeline. That's an expensive piece of kit and they must be planning to pour a lot of concrete, over a period of time that makes it economical to rent it in and set it up instead of hiring mobile pump trucks on the days they pour.

I wonder how far down this building will go.

Also: those things are noisy. Expect a hell of a racket and lots of vehicle movements for the concrete itself.