Where were Paul and Barnabas sent to settle the dispute over circumcising Gentile believers?

Answer: Jerusalem

After sharp debate with men from Judea, Paul and Barnabas were appointed to go up to Jerusalem to the apostles and elders.

“And after engaging these men in sharp debate, Paul and Barnabas were appointed, along with some other believers, to go up to Jerusalem to see the apostles and elders about this question.”— Acts 15:2 (BSB)