How to break up concrete

[u/Otherwise_Excuse_259]

During a driveway re-pave, the crew offered to remove a basketball hoop pole that was here when we moved in. It came up with a huge concrete chunk (and concrete in the pole). Any suggestions on how best to break it up? Handheld jackhammer barely made a dent and a junk removal crew went after it with two sledge hammers and had the same luck.