How did ancient Jerusalem resist Babylon's siege for so long?

NARRATOR: It's the seventh century B.C. Babylon, a superpower of the era, is preparing for world conquest. The Bible describes this in detail. The Babylonians succeed with brute force and fighting valor. One objective, Jerusalem, drives them to desperation. They lay siege to the city for over a year. Success was long in coming. How could Jerusalem, isolated as it was, withstand their attacks for so long? The ancient aqueducts might offer an explanation. Unnoticed by the besiegers, they continued to supply the city with fresh drinking water. The actual water source lay outside of the city. A risky situation. This is why the Jerusalemites did not hesitate to build an underwater conduit that transported the water into the city, depositing it into a lake. The lake supplied the city's inhabitants with all the freshwater they needed. The source itself was covered up, so as not to be discovered. But when was this tunnel built? Did it exist at the time of the Babylonian attack? Israeli researchers went to search for evidence. The geologist takes samples from the walls, gathering deposits accumulated over millennia. With them, he hopes to learn about the origins of the aqueduct. In the lab the rock samples tell him more about when the conduit was built and its age, using modern technology to retrace biblical narrative.

DR. ARYEH SHIMRON: "So we have these techniques showing that indeed the fracturing aqueduct in ancient Jerusalem is ancient. It was probably carved out by engineers of King Hezekiah and, indeed, it is the oldest biblical structure which has been carefully and convincingly dated."

NARRATOR: The sophisticated and ingenious tunnel helped Jerusalem's inhabitants resist the Babylonian charge for more than a year. This unsettled the otherwise triumphant Babylonian armies. But then the breakthrough. With decisively superior numbers, the besiegers breach the city walls. That was most probably in the year 587 B.C. It was the end of ancient Jerusalem, the city that used furtive artifice to supply itself with water and withstand the siege for so long.