JERUSALEM ( CNN ) -- An archaeological dig in Jerusalem has turned up a 3,700-year-old wall that is the largest and oldest of its kind found in the region , experts say . The wall is built of enormous boulders , confounding archaeologists as to how ancient peoples built it . Standing 8 meters ( 26 feet ) high , the wall of huge cut stones is a marvel to archaeologists . `` To build straight walls up 8 meters ... I do n't know how to do it today without mechanical equipment , '' said the excavation 's director , Ronny Reich . `` I do n't think that any engineer today without electrical power [ could ] do it . '' Archaeologist Eli Shukron of the Israel Antiquities Authority added , `` You see all the big boulders -- all the boulders are 4 to 5 tons . '' The discovered section is 24 meters ( 79 feet ) long . `` However , it is thought the fortification is much longer because it continues west beyond the part that was exposed , '' the Israel Antiquities Authority said in a news release . It was found inside the City of David , an archaeological excavation site outside the Old City of East Jerusalem on a slope of the Silwan Valley . The wall is believed to have been built by the Canaanites , an ancient pagan people who the Bible says inhabited Jerusalem and other parts of the Middle East before the advent of monotheism . Watch report on the discovery of the ancient wall » . `` This is the most massive wall that has ever been uncovered in the City of David , '' Reich and Shukron said in a joint statement about the find . It marks the first time `` that such massive construction that predates the Herodian period has been discovered in Jerusalem . '' It appears to be part of a `` protected , well-fortified passage that descends to the spring tower from some sort of fortress that stood at the top of the hill , '' according to the joint statement . The spring `` is located in the weakest and most vulnerable place in the area . The construction of a protected passage , even though it involves tremendous effort , is a solution for which there are several parallels in antiquity , albeit from periods that are later than the remains described here . '' Such walls were used primarily to defend against marauding desert nomads looking to rob the city , said Reich , a professor at the University of Haifa . `` We are dealing with a gigantic fortification , from the standpoint of the structure 's dimensions , the thickness of its walls and the size of the stones that were incorporated in its construction , '' the joint statement said . Water from the spring is used by modern inhabitants of Jerusalem . `` The new discovery shows that the picture regarding Jerusalem 's eastern defenses and the ancient water system in the Middle Bronze Age 2 is still far from clear , '' Reich said . `` Despite the fact that so many have excavated on this hill , there is a very good chance that extremely large and well-preserved architectural elements are still hidden in it and waiting to be uncovered . '' CNN 's Kevin Flower contributed to this report .
Made of boulders weighing 4 to 5 tons , the 3,700-year - old wall is 30 feet high . Archaeologist : ` ` I do n't know how to do it properly without mechanical equipment '' The wall appears to have been used to defend passages that used to spring . It is believed to have been built by Canaanites .