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. It is one of the largest building blocks in the world.
The stone's exposed face can be freely measured and is 13.55 metres (44.5 ft) long and 3.3 metres (11 ft) high, but its width, or depth, is hidden within the wall.
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 ft).
The resulting calculated weight of the stone block is of 250–300 tonnes.
Previous estimates of the stone's depth were of 16.5 metres (54 ft), a multiple of the GPR measurement, and led to a calculated total weight of 567 tonnes. Other pre-2006 sources circulated similar figures, namely 550 to 600 t. The Western Wall Heritage Foundation (WWHF) website still indicates, as of March 2020, an "estimated" depth of between 2–4.6 metres (6.6–15.1 ft), with an estimated weight of "several hundred tons", thus moderating its former claim of an estimated weight of 517 tonnes (570 short tons);
The stone is located in a section of the Western Wall (in the broader meaning of the term) north of Wilson's Arch, below ground level, and can be accessed through the Western Wall tunnels. It is part of the "Great Course", a name used by the WWHF for the tallest and longest course (layer of stones) of the Western Wall. Its stone blocks are of Herodian age, and the stones next to the Western Stone are, in sequence, 2 metres (6.6 ft), 12.12 metres (39.8 ft), and 8 metres (26 ft) long, respectively.
- "Facts and Figures: The Great Course (Nidbach Raba)". Western Wall Heritage Foundation. Retrieved 2020-03-20.
- The Utah Monolith Has an Ancient History, Haaretz
- Jol, H. M.; et al. (2006). "Publications, #79". Retrieved 13 August 2015.
- Harry M. Jol, Paul D. Bauman and Dan Bahat: Looking into the Western Wall, Jerusalem, Israel. Proceedings of the Eleventh International Conference on Ground Penetrating Radar (GPR 2006), June 19 - 22, The Ohio State University, Columbus, Ohio, USA, Papers on CD-ROM. Also in: Dan Bahat, The Jerusalem Western Wall Tunnel, Israel Exploration Society, 2013, pp. 395-40.
- The History Channel, in "Lost Worlds of King Herod", cited a 16.5 m depth and 567 tonnes estimate
- Dan Bahat: Touching the Stones of our Heritage, Israeli ministry of Religious Affairs, 2002
- "The Story of the Kotel: Facts and Figures: The Western Wall Tunnels". Western Wall Heritage Foundation. Archived from the original on 2005-12-14.