2 Chronicles 25:23

23 And Joash king of Israel captured Amaziah king of Judah, the son of Joash, son of a Ahaziah, at Beth-shemesh, and brought him to Jerusalem and broke down the wall of Jerusalem for 400 cubits,
A  cubit was about 18 inches or 45 centimeters
from c the Ephraim Gate to the Corner Gate.
Copyright information for ESV