Scholars believe King Hezekiah commissioned the tunnel for security reasons to supply his subjects with water during an imminent siege by the Assyrians.
"The spring water comes out in the valley and not in the city," said Frumkin. "The ultimate solution was to bring the water into the city. The tunnel takes the water by gravitation down to a pool which is built inside the city."
The construction of the tunnel is described in detail in Kings and Chronicles in the Bible. Scholars have long debated its historical importance.
"In the Bible, the city [of Jerusalem] was saved by a miracle," said Hershel Shanks, editor of Biblical Archaeology Review. "However, the Bible does tell us that Hezekiah built this tunnel and apparently that is what enabled the Israelites to withstand the siege."
At one point, after the tunnel was built, the spring is believed to have been sealed to conceal it from the enemy. Most people only knew the Siloan Pool and lower end of the tunnel. It wasn't until the late Middle Ages when people walked into the tunnel that they found it was connected to the spring.
"We have known about the tunnel for a long time," said Frumkin, who began researching the tunnel while he was in high school in the late 1960s. "It just hasn't been dated."
Hard to Date
Modern equivalents of structures described in the Bible are hard to locate and date. Most sites are not associated with enough geographical information to be identified, and many structures have been destroyed during warfare. Others, like the Temple Mount in Jerusalem, are easily identified but impossible to study because of political reasons.
"The main problem is that we don't have a lot of material that can be dated," said Frumkin. "Unlike in archaeological dating, which relies on comparison of artifacts, it's very rare to have material available for radiometric dating."
There are still many structures described in the Bible, like some of the gates leading into ancient Jerusalem, that have not been dated.
"It's quite rare to be able to go into structures that were constructed thousands of years ago to try to understand the people who lived during this time," said Frumkin. "But if we can date the structure, we will be able to know if what is written in the Bible is real."
A summary of the research is described in today's issue of the science journal Nature.
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