The Western Stone is a monolithic stone ashlar block forming part of the lower level of the Western Wall in Jerusalem. This largest stone in the Western Wall is visible within the Western Wall Tunnel. With an estimated weight of 517 tonnes (570 short tons), it is one of the largest building blocks in the world. The stone, located in the wall section north of Wilson's Arch, is 13.6 meters (44.6 feet) long and 3 metres (9.8 feet) high and has an estimated width of 3.3 meters (10.8 feet). In June 2006, Harry M. Jol, from the University of Wisconsin–Eau Claire, performed GPR measurements to determine the depth of the stone. The conclusion of his team was that its depth ranges from approximately 1.8 to 2.5 metres (5.9 to 8.2 feet).