During the early Iron Age, a massive wall was constructed around the crown of the hill and a huge pool was cut in the living rock just inside the wall. In a first phase it was cut with a diametre of 11.8 m to a depth of 10.8 m, with a spiral staircase of 79 steps cut into the walls of the pool, and in a second phase a tunnel was added that continues downwards to a water chamber 24 m below the level of the city. It is possible, but cannot be proven, that this structure is the "pool of Gibeon" of . Later in the Iron Age, another tunnel of 93 steps was constructed to a better water source below the city starting from a point near the pool. A second access point to this source from the base of the hill is still in use today.