Before which gate did the people gather to hear Ezra read the Law?

Answer: The Water Gate

All the people gathered in the square before the Water Gate, and Ezra read the Law there from early morning until noon.

“At that time all the people gathered together in the square before the Water Gate, and they asked Ezra the scribe to bring out the Book of the Law of Moses, which the LORD had commanded for Israel.”— Nehemiah 8:1 (BSB)