A beautiful aqueduct, standing 1.50 meters high and built of large stones, has been situated for almost two millennia right under one of the most familiar and traveled places in Jerusalem – beneath the road that leads from Jaffa Gate toward the David Citadel Museum and the shops on David Street.
The High-Level Aqueduct of Jerusalem, which dates from the second-third century CE, was exposed in excavations the Israel Antiquities Authority is conducting, with funding provided by the Jerusalem Development Authority for the purpose of replacing the infrastructure in the region.
According to Dr. Ofer Sion, excavation director on behalf of the Israel Antiquities Authority,The side of the aqueduct was discovered during the course of the excavation. When we removed the stones in its side and peeked into it we saw a splendidly built aqueduct covered with stone slabs where one can walk crouched down for a distance of approximately 40 meters. It is very exciting to think that no one has set foot there for many hundreds of years”. According to Sion, “The noted Land of Israel scholar, Dr. Conrad Schick, described a specific section of the aqueduct in a survey he conducted at the end of the nineteenth century. In 1898 a building was erected in this area which afterward became what we know of today as the Imperial Hotel. Schick’s documentation provided us with the clue that led to exposing this section of the aqueduct”.
The aqueduct is c. 60 centimeters wide and 1.5 meters high. Shafts were exposed at fifteen meter intervals or so that allowed the ancients to check the state of the aqueduct from what was the surface level in those days. 
Until the end of the SecondTemple period, in the first century BCE, Jerusalem’s water supply was derived from the Gihon Spring; however, as the number of residents steadily increased, the city’s water resources proved insufficient. The shortage of water was the principal factor that led to the construction of Jerusalem’s magnificent waterworks during Herod’s reign.
Gravity and very sophisticated engineering were employed to carry water to the city from springs located in the Hebron Hills, which were sufficiently high enough to convey the water by way of aqueducts to Jerusalem. The water was brought dozens of kilometers on its way to Jerusalem until it reached Solomon’s Pools and was distributed from there via two main aqueducts: the Low-Level Aqueduct and the High-Level Aqueduct. The High-Level Aqueduct conveyed water to the high part of the city where King Herod’s palace and Hezekiah’s Pool were situated, the latter being the main source of water for all those arriving in the city; and the Low-Level Aqueduct carried water to the Temple Mount and the Temple.
According to Dr. Sion, “For now, we can date the section of the aqueduct that was exposed to the second century CE, to the time of the pagan city Aelia Capitolina, which was built on the ruins of Jerusalem following the Bar Kokhba Revolt in 135 CE. Presumably, however, the aqueduct was first constructed in the days of Herod, as we know from other places along its route, particularly in the Bethlehem area. Archaeological research has shown that the total length of the aqueduct, which begins at Solomon’s Pools, is about 13 kilometers.