A geophysical survey, including ground penetrating radar, has revealed an underground shaft at the site of Tel Lachish. The excavators believe this could be an ancient water shaft similar to those found in Jerusalem, Gibeon and Hazor. The shaft itself appears to be up to 33 feet (10 meters) wide and 66 feet (20 meters) deep. It's possible that a king of Judah (or a prior Canaanite king) built the the underground tunnel to bring water from outside the city walls to the residents inside the city. According to the Bible, Rehoboam, the son of Solomon, fortified Lachish (2 Chr. 11:5-7).