The Siloam Tunnel is one of the greatest adventures of a Jerusalem tour. It is a highlight of the visit to the City of David, the earliest remnants of Jerusalem, where visitors experience an amazing engineering feat: the 1,500-foot-long-tunnel created by King Hezekiah in 701 BCE to protect Jerusalem’s water source, the Gihon Spring, from the invading Assyrians (2 Chron. 32:2-4).
Near the exit of the tunnel, the British explorer Captain Charles Warren (who first rediscovered it in 1867) found an ancient Hebrew inscription describing the construction. It says a team of diggers started at each end, listening for the sound of each other's pickaxes, and eventually met in the middle!
As visitors slosh through the water, their flashlights pick up the marks of the ancient pickaxes, going in one direction until the meeting point and then going the other way. The water-walk takes about 45 minutes, and is recommended for visitors of all ages tall enough to wade through about two feet of flowing water. For land-lubbers, new excavations have revealed another tunnel, now dry but that still gives a sense of the greatness of Jerusalem's long ago laborers, monarchs and engineers.