In 701 BCE, Jerusalem faced an existential threat. The mighty Assyrian Empire, which had already conquered the Northern Kingdom of Israel, now set its sights on the Southern Kingdom of Judah and its capital city. As the Assyrian army under King Sennacherib laid siege to Jerusalem, King Hezekiah of Judah prepared for a fight to the death. Along with fortifying the city walls, he launched a daring infrastructure project to secure Jerusalem‘s vital water supply – a tunnel carved through bedrock to secretly channel water from the Gihon Spring into the city.
Nearly three millennia later, this incredible feat of ancient engineering still endures. Known today as Hezekiah‘s Tunnel or the Siloam Tunnel, the 1,750-foot long subterranean aqueduct continues to carry water and stands as a testament to the ingenuity and determination of Jerusalem‘s ancient defenders. But just how did they construct such a marvel, and how long did it take? Let‘s dig into the fascinating history of Hezekiah‘s Tunnel.
Jerusalem Under Siege
To understand the story behind Hezekiah‘s Tunnel, we need to set the scene. In the late 8th century BCE, the Neo-Assyrian Empire was the undisputed superpower of the Near East, having conquered vast swaths of territory from Mesopotamia to Egypt. After the Assyrians invaded and destroyed the Northern Kingdom of Israel in 722 BCE, they soon turned their attention to the Southern Kingdom of Judah.
According to the biblical account in 2 Kings 18-19, King Hezekiah of Judah initially paid tribute to the Assyrian king Sennacherib but later rebelled, prompting an Assyrian invasion around 701 BCE. Sennacherib‘s army swept through Judah, conquering 46 cities and trapping Hezekiah within the walls of his capital Jerusalem.
Hezekiah took decisive action, as recorded in 2 Chronicles 32:2-4:
"When Hezekiah saw that Sennacherib had come and that he intended to wage war against Jerusalem, he consulted with his officials and military staff about blocking off the water from the springs outside the city, and they helped him. They gathered a large group of people who blocked all the springs and the stream that flowed through the land. ‘Why should the kings of Assyria come and find plenty of water?‘ they said."
Archaeology confirms that Hezekiah heavily fortified Jerusalem in preparation for the Assyrian onslaught. He constructed a massive wall around the Western Hill and reinforced the Millo platform in the City of David. But his most ambitious project was a secret underground tunnel to secure Jerusalem‘s water supply.
Tapping the Gihon Spring
Jerusalem‘s main water source was the Gihon Spring, located in the Kidron Valley just outside the eastern city wall. While this provided ample water, it was vulnerable to the enemy laying siege. Hezekiah‘s solution was to construct a tunnel channeling water from the spring into the Pool of Siloam within the city walls, denying this resource to the Assyrians and securing it for Jerusalem.
Carved through solid limestone bedrock, the S-shaped tunnel was chiseled out by two teams of excavators starting at opposite ends and meeting in the middle. The Siloam Inscription, found carved into the tunnel wall in 1880, commemorates this incredible achievement in ancient Hebrew:
"… the tunneling through. And this was the way in which it was cut: while [the excavators lifted] their axes, each crew toward its counterpart, and while there were still three cubits to be cut, the voice of a man was heard calling to his comrade, for there was a fissure in the rock on the right… the excavators hacked toward each other, axe against axe, and the water flowed…"
Surveying and Engineering Challenges
Directing two tunneling crews to precisely meet hundreds of feet underground, armed only with iron chisels and oil lamps, was no simple feat. How did Hezekiah‘s engineers survey and align the tunnel‘s path?
The most commonly accepted theory is that they used a "sounding" technique, hammering on the rock and listening for the noise of the other crew to guide their direction. However, this crude method likely accounts for the curving and zig-zagging bore of the tunnel.
Some scholars have proposed that vertical shafts were sunk from above at intervals to help direct the diggers and provide ventilation. However, no remains of such guiding shafts have been definitively identified. It‘s also possible that Hezekiah‘s engineers had sophisticated surveying and leveling methods that have been lost to history.
The tunnel follows a sinuous ‘S‘ curve for 1,750 feet (533 meters) and has an average height of 6 feet (1.8 meters). Its width varies from around 2 to 4 feet. The floor gradually slopes down from the spring to the Pool of Siloam, a total elevation difference of about 12 feet, allowing the water to flow naturally.
While the tunnel served a defensive purpose, the incredible effort invested in cutting a long winding tunnel rather than a short direct one suggests that concealing the location of the spring from the enemy was a priority. The curving path, small profile, and flowing water also would have made it harder for infiltrators to traverse the tunnel.
Construction Time Estimates
So just how long did this marvel of ancient engineering take to construct? Unfortunately, no definitive record of the tunnel‘s construction timeline survives, leaving us to deduce estimates based on archaelogical and textual evidence.
Clues in the biblical account suggest the tunnel was completed before Sennacherib‘s siege of Jerusalem in 701 BCE. 2 Kings 20:20 notes that Hezekiah "made the pool and the tunnel by which he brought water into the city." Some scholars argue this phrasing indicates the tunnel was already finished when the Assyrians arrived.
However, estimates for the tunnel‘s actual construction time span from as little as a few months to as long as four years. Variables like the number of laborers, available tools and techniques, and the hardness of the bedrock all factor into the calculation.
Archaeologist Aren Maeir estimates that with crews working from both ends, hewing an average of 2 feet (0.6 meters) per day through the limestone, the tunnel could have been completed in about 2-3 years. This is broadly consistent with the timeline for Hezekiah‘s other massive preparations ahead of the siege.
For comparison, the Euphalios Tunnel on the Greek island of Samos, built around the same time as Hezekiah‘s Tunnel, is over twice as long at 3,400 feet. Ancient accounts state it took a decade and up to 1,000 workers to construct. The shorter Siloam Tunnel likely required far fewer laborers and less time, even with its curving path.
Rediscovery and Exploration
After the Assyrian threat passed, Hezekiah‘s Tunnel faded from the historical record for centuries. It wasn‘t until 1838 that American biblical scholar Edward Robinson rediscovered the tunnel, venturing into its dark recesses by candlelight. Further explorations and excavations followed over subsequent decades.
In 1880, a local Greek Orthodox priest‘s young son discovered the ancient Paleo-Hebrew inscription now known as the Siloam Inscription while wading through the tunnel. It was later carefully chiseled out and is now displayed in the Istanbul Archaeological Museum.
According to the Israel Antiquities Authority, "the Siloam Inscription is the oldest extant Hebrew inscription from ancient Jerusalem and a key source for understanding the history of the city in the First Temple period." It provides invaluable confirmation of both the tunnel‘s age and biblical accounts of its construction.
Walking Through History
Today, the City of David National Park offers visitors the chance to wade through Hezekiah‘s Tunnel, which still carries flowing spring water. Equipped with a flashlight and wading through the calf-deep water, you can follow in the footsteps of the ancient workers who chiseled the tunnel by hand.
The tunnel‘s narrow, undulating passageway is not for the claustrophobic. At its tightest points, the tunnel is less than 2 feet wide. Visitors must crouch and even turn sideways to squeeze through. The cool, dark water and dripping walls transport you back in time as you marvel at the ancient masons‘ work.
After several hundred feet, the tunnel widens slightly. Here you can appreciate the incredible precision and coordination it must have taken for the diggers approaching from opposite directions to meet. A small plaque marks the probable location where the two tunneling crews broke through and shook hands over 2,700 years ago.
Emerging from the far end of the tunnel into daylight at the Pool of Siloam, you gain a newfound appreciation for the ancient Judean engineers who toiled underground to save their city. While Jerusalem would eventually fall to later conquerors, the legacy and wonder of Hezekiah‘s Tunnel endures to this day.
Enduring Legacy
Hezekiah‘s Tunnel stands as one of the greatest accomplishments of ancient engineering in the Near East. The intricate underground waterway not only secured Jerusalem‘s vital water supply against the Assyrian siege, but also demonstrated the kingdom of Judah‘s skill, ingenuity, and resolve in the face of existential threat.
The tunnel‘s winding path and remarkable construction have sparked debate and admiration among biblical scholars and archaeologists for generations. How did the ancient engineers calculate the slope to ensure proper water flow? What surveying and mapping techniques allowed the diggers to align the tunnel? The answers remain uncertain, but the achievement is undeniable.
As archaeologist Ronny Reich summarized, "Digging the tunnel was a tremendous accomplishment, requiring extraordinary levels of planning, resources, and organizational skill in addition to the ability to perform the excavation itself…The tunnel is therefore a reflection of the power and capabilities of Judean society at the end of the eighth century B.C.E."
Nearly three millennia after its construction, Hezekiah‘s Tunnel continues to inspire and amaze. It draws visitors from around the world, from pilgrims retracing biblical history to tourists marveling at Jerusalem‘s ancient wonders. Its enduring presence is a testament to the ingenuity, faith and determination of a city that has survived and thrived for thousands of years.
So the next time you find yourself in Jerusalem, be sure to wade through this remarkable tunnel and immerse yourself – quite literally – in the living history of one of the world‘s most ancient and fascinating cities. Just don‘t forget your flashlight!
Sources and Further Reading
- Reich, Ronny. "Hezekiah‘s Tunnel." Encyclopaedia Judaica, edited by Michael Berenbaum and Fred Skolnik, 2nd ed., vol. 9, Macmillan Reference USA, 2007, pp. 92-93.
- Frumkin, Amos, and Aryeh Shimron. "Tunnel engineering in the Iron Age: Geoarchaeology of the Siloam Tunnel, Jerusalem." Journal of Archaeological Science 33.2 (2006): 227-237.
- Maeir, Aren. "Hezekiah‘s Tunnel: The Archaeological Evidence." Bible History Daily, Biblical Archaeology Society, 22 Sept. 2017, https://www.biblicalarchaeology.org/daily/biblical-sites-places/jerusalem/hezekiahs-tunnel-the-archaeological-evidence/.
- Gill, Dan. "How They Met: Geology Solves Long-Standing Mystery of Hezekiah‘s Tunnelers." Biblical Archaeology Review, vol. 20, no. 4, 1994, pp. 20–33, 64.
- "The Siloam Inscription: Hezekiah‘s Tunnel Revisited." Israel Ministry of Foreign Affairs, 20 Dec. 2015, https://mfa.gov.il/MFA/IsraelExperience/History/Pages/The-Siloam-Inscription-Hezekiahs-Tunnel-Revisited.aspx.
