Hezkiah's water tunnel was dug by hand over 2700 years ago and is still working today. We walked through this amazing feat of engineering, which is 530 metres long, under the City of Jerusalem. It was created as a defensive measure to bring the water from the Gihon spring into the city, as it was the only source of water and being outside the city walls, vulnerable to attack. Two teams started from opposite ends and amazingly succeeded in meeting half way. A 'must do' when in Jerusalem.