'Outer' in the Bible

Now David was sitting between the inner and outer gates, and the watchman went up to the roof over the gate at the wall. When he looked, he saw a man running by himself.

So Joab's men came and laid siege against him in Abel of Beth Maacah. They prepared a siege ramp outside the city which stood against its outer rampart. As all of Joab's soldiers were trying to break through the wall so that it would collapse,