Researchers from Cairo University and the Technical University of Munich (TUM), working under the ScanPyramids project, have identified two previously undetected, air-filled anomalies behind the eastern face of the Menkaure Pyramid at Giza. The discovery lends strong support to a long-standing hypothesis that this side of the monument may conceal a second entrance.
Using a combination of non-destructive testing (NDT) techniques—Ground Penetrating Radar (GPR), Ultrasonic Testing (UST), and Electrical Resistivity Tomography (ERT)—the researchers were able to reveal internal voids without causing any damage to the ancient structure.
The east face of the pyramid, known for a compact zone of well-polished granite blocks measuring about four meters high and six meters wide, has long intrigued experts for its resemblance to the finishing around the pyramid’s known northern entrance. This visual clue, first noted in 2019, guided a detailed NDT-based mapping of the lower courses of the 60-meter-high structure.
The fused dataset from the three NDT methods revealed two air-filled voids directly behind the polished granite zone. The first void begins approximately 1.4 meters below the surface and measures about 1.5 by 1.0 meters, while the second starts at 1.13 meters and measures roughly 0.9 by 0.7 meters. Both cavities are slightly inclined and appear positioned symmetrically relative to the polished area.
Christian Grosse, Professor of Non-Destructive Testing at TUM, said the methodology allows “very precise conclusions” on internal features while protecting the structure, adding that “the hypothesis of another entrance is very plausible” and that the results move the team closer to confirming it.
The study, published in NDT & E International, emphasizes that the current techniques can define the starting points and dimensions of the voids but cannot yet determine their full extent. The authors suggest further investigations using complementary non-invasive tools such as infrared thermography, micro-gravimetry, or cosmic-ray muography to map potential continuations.
This multidisciplinary approach underscores the growing role of NDT in heritage preservation and archaeological discovery, offering insight into ancient engineering without physical intrusion.
