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Revolutionary scanning technology has identified two concealed air-filled anomalies behind the eastern facade of Egypt’s Menkaure Pyramid, providing the first scientific evidence to support a long-standing hypothesis about a second entrance to the ancient structure.
An international research team from Cairo University and the Technical University of Munich (TUM), working as part of the prestigious ScanPyramids project, has made a breakthrough discovery at the smallest of Giza’s three main pyramids. Using advanced non-destructive testing methods including radar, ultrasound, and electrical resistivity tomography, the scientists detected two distinct air-filled voids concealed approximately 1.4 meters and 1.13 meters beneath a section of remarkably polished granite blocks on the pyramid’s eastern face. These findings mark the first time structural anomalies have been identified in this location, lending credibility to theories first proposed by researcher Stijn van den Hoven in 2019.
The Mystery of the Polished Stones
The eastern facade of the Menkaure Pyramid has puzzled researchers for years due to an unusual architectural feature. Over an area measuring approximately four meters high and six meters wide, the granite blocks display an exceptional level of polish that stands in stark contrast to the rougher stonework found elsewhere on the structure. This distinctive smoothness is otherwise only observed around what is currently recognized as the pyramid’s sole entrance on the northern side. The similarity between these two locations sparked Van den Hoven’s hypothesis about a potential hidden entrance, which has now received compelling support from scientific investigation.
(a) the Northern face of the Menkaure Pyramid and (b) a close-up view of the main entrance, and (c) the polished part of the Eastern face (subject of interest in this study). (Helal et al/NDT & E International)
The Menkaure Pyramid, built during the Fourth Dynasty reign of Pharaoh Menkaure around 2500 BC, stands more than 60 meters tall and represents the third-largest pyramid on the Giza Plateau. While smaller than its famous neighbors—the pyramids of Khufu and Khafre—it has long been a subject of archaeological fascination. The structure’s unique characteristics, including its granite casing stones and interior chambers, have provided valuable insights into ancient Egyptian construction techniques and burial practices.
Cutting-Edge Technology Reveals Hidden Structures
The research team employed a sophisticated combination of three complementary non-destructive testing methods to probe beneath the pyramid’s surface without causing any damage to the invaluable ancient structure. Electrical Resistivity Tomography (ERT) was utilized first, with measurements taken along four long parallel profiles using specialized stainless steel mesh electrodes. The data was then processed through a three-dimensional inversion algorithm to create detailed images of the subsurface electrical properties.
Researchers setting up the scanning equipment at the Menkaure Pyramid. (ScanPyramids Project)
Following the ERT surveys, Ground Penetrating Radar (GPR) equipped with dual-frequency antennas operating at 200 and 600 MHz was deployed in a focused grid pattern over the area of interest. Additionally, a 16-channel Ultrasonic Testing (UST) array device provided high-resolution data about the internal structure of the stonework. The crucial breakthrough came when researchers applied an Image Fusion technique to merge all three datasets, enabling precise correlation of features detected by each independent method.
The two detected anomalies measure 1 meter high by 1.5 meters wide and 0.9 meters by 0.7 meters respectively. According to the research team’s findings published in the journal NDT & E International, the precise determination of these air-filled voids was only possible through the innovative combination and fusion of all three measurement techniques. To validate their interpretation, the scientists conducted extensive numerical simulations considering various possible scenarios under real-world conditions, all of which supported the conclusion that the detected anomalies represent air-filled spaces rather than variations in stone density or composition.
Electrical Resistivity Tomography (ERT) scan results showing presence of anomalies A1 and A2. (Helal et al/NDT & E International)
Implications for Understanding Ancient Architecture
Professor Christian Grosse of TUM, an expert in non-destructive testing, emphasized the significance of this discovery for both Egyptian archaeology and the field of archaeological science. “Following the significant validation of a hidden corridor in the Pyramid of Cheops in 2023, ScanPyramids has once again succeeded in making an important finding in Giza,” Grosse stated in the research announcement. He noted that the testing methodology developed by the team allows very precise conclusions to be drawn about the pyramid’s interior without damaging the valuable structure.
The hypothesis of a second entrance to the Menkaure Pyramid carries substantial implications for understanding ancient Egyptian architectural practices and burial customs. If confirmed through further investigation, it would suggest a more complex design than previously understood and could potentially provide access to undiscovered chambers or passages within the pyramid. Such a find would be consistent with the sophisticated engineering capabilities demonstrated throughout the Fourth Dynasty, when Egyptian pyramid construction reached its zenith.
The ScanPyramids project, which began in 2015, has revolutionized the study of Egypt’s pyramids through the application of modern physics and advanced imaging technologies. Previous successes include the 2017 discovery of a large void in the Great Pyramid of Khufu using muon radiography and the 2023 confirmation of a hidden corridor above the main entrance to the same structure. These discoveries have consistently demonstrated that even the most extensively studied ancient monuments still harbor secrets waiting to be revealed through innovative scientific approaches.
Professor Grosse concluded that “the hypothesis of another entrance is very plausible, and our results take us a big step closer to confirming it.” The research team plans to conduct additional investigations to further characterize the detected anomalies and determine the most appropriate methods for potentially accessing the suspected entrance without compromising the structural integrity of this irreplaceable monument. The findings represent a remarkable convergence of archaeological hypothesis, historical observation, and cutting-edge scientific technology, opening new chapters in our understanding of one of humanity’s most enduring architectural achievements.
Top image: The Menkaure Pyramid at Giza with its distinctive granite casing stones visible at the base. Source: David Broad/CC BY 3.0
By Gary Manners
References
Helal, K., Pugacheva, P., Allam, H., et al. 2025. Detection of two anomalies behind the Eastern face of the Menkaure Pyramid using a combination of non-destructive testing techniques. Available at: https://www.sciencedirect.com/science/article/pii/S096386952500012X
Phys.org. 2025. Air-filled anomalies in Menkaure Pyramid could indicate a new entrance. Available at: https://phys.org/news/2025-11-air-anomalies-menkaure-pyramid-entrance.html
