The Bible says Joab conducted his sneak attack on the Jebusite city using a water conduit—tsinnor in Hebrew (see 2 Samuel 5:8). The weak point allowed him and his men to storm the city and claim it for King David.

Toward the end of an archaeological dig in 2008, while excavating around the top half of the famous Stepped Stone Structure, Eilat Mazar accidentally discovered an opening to a tunnel dating to the 10th century b.c.

“The tunnel’s characteristics, date and location testify with high probability that the water tunnel is the one called tsinnor in the story of King David’s conquest of Jerusalem,” said Dr. Mazar. Layers of debris dating to the end of the First Temple period (sixth century b.c.) had buried the entrance to the tunnel. After stumbling upon the opening, Dr. Mazar investigated the tunnel. She found that it ran from north to south and was wide enough for one person to pass through.

Both ends of the tunnel are blocked by debris and fallen stones—yet it still measures over 160 feet long. Dr. Mazar says that further excavation would require constructing proper reinforcements to support the subterranean structure.

The tunnel walls follow a natural cavity in the bedrock that runs along the upper part of the eastern slope of the City of David. She believes the tunnel was integrated into its construction and might have been used to channel water to a man-made pool built on the southeast side of the palace, referred to in Nehemiah 3:16.

“Toward the end of the First Temple period (sixth century b.c.), the tunnel was converted to an escape passage, perhaps used in a manner similar to King Zedekiah’s escape during the Babylonian siege (2 Kings 25:4),” Mazar wrote in a press release. “During this phase, additional walls were constructed in order to prevent the possibility of anyone entering the tunnel from the slope of the hill and to prevent penetration of debris inside the tunnel. Complete oil lamps were found on the ground of the tunnel, characteristic of the end of the First Temple period. These lamps testify to the tunnel’s last use.”

Once the Babylonians laid siege upon the city in 585 b.c., however, the tunnel was lost from world view and forgotten—until now.

Dr. Mazar called the discovery “completely unexpected.” And since it occurred near the end of a digging season, she believes there is much more to be learned about the passageway. “We have a general knowledge of the tunnel,” she said, “but we are far from having a complete picture.