In Athens, where was Paul brought to explain the new teaching he was presenting?

Answer: The Areopagus

The Athenians brought Paul to the Areopagus and asked, "May we know what this new teaching is that you are presenting?"

“So they took Paul and brought him to the Areopagus, where they asked him, “May we know what this new teaching is that you are presenting? For you are bringing some strange notions to our ears, and we want to know what they mean.””— Acts 17:19-20 (BSB)