In a groundbreaking new study, Israeli geologists Aryeh Shimron and Amos Frumkin mapped the geological and manmade features of Hezekiah’s Tunnel. Their map provides important insights into how the tunnel was (and was not) constructed. Shimron and Frumkin found no geological evidence of a continuous karstic channel along the length of the tunnel, as geologist Dan Gill had proposed. Shimron and Frumkin found that nearly all of the natural fractures in the surrounding rock—the geological paths along which karstic channels form—run across, and not parallel to, the line of the tunnel. (The photo shows one of these numerous fractures running perpendicular to the path of the tunnel.) Thus, the tunnel could not have originally been a natural karstic channel because the necessary geological conditions simply were not present. But how did the two teams find each other?