New findings beneath the desert floor hint at entrances to long-lost chambers.

• Ground-penetrating radar has helped archeologists identify buried wonders below the surface.
• Now, a study from Japanese and Egyptian researchers reveals the discovery of an L-shaped structure along with an accompanying anomaly right next to the Great Pyramids of Giza.
• Although its impossible to know for sure what the anomaly is, the researchers guess that the L-shaped discovery could be an entrance to a deeper structure.

In the world of archeology, few tools have revolutionized the field as much as ground-penetrating radar (GPR). This geophysical technique uses radar pulses to image the subsurface. Similar techniques have uncovered Viking longships in Norway, revealed lost civilizations in the Amazonian jungle, and even entire Roman cities without ever putting a shovel into dirt.

And GPR has once again delivered near one of the most well-excavated sites in the world—the Great Pyramids of Giza.

Researchers led by Tohoku University’s Motoyuki Sato used GPR—along with a method known as electrical resistivity tomography (ERT), which uses electrical resistance to map underground structures—to discover what’s being described as an “L-shaped anomaly” in the western cemetery near the world-renowned pyramids.

According to the team’s research paper, published in the journal Archeological Prospection, the structure is roughly 6.5 feet from the surface, measures 33 feet in length, and was backfilled after construction.

“The Western Cemetery at Giza is known as an important burial place of members of the royal family and high-class officers,” the paper reads. “In the initial survey by GPR and ERT we found an anomaly in the north of the survey site. The area of the anomaly could be established approximately, but the structure and the location were unclear.”

Below this L-shaped structure was an anomaly, lying 16 to 33 feet down, that the researchers described as “highly electrically resistive.” Such an anomaly could have a few explanations, but the team identified two main possibilities—a mixture of sand and gravel, or “sparse spacing with air voids.” While we know that the surrounding area (built roughly 4,500 years ago, around the same time as its adjacent pyramids) is filled with flat-roofed tombs known in Arabic as mastaba, the stretch of sand where the anomaly was found has not been nearly as intensely excavated, largely because the area sported no impressive structures to warrant a thorough investigation.

So, what exactly could this L-shape structure and its lower anomaly represent? Speaking with Live Science, Sato said the structure is likely not natural, as the shape is too sharp.

“It may have been an entrance to the deeper structure,” Sato and his colleagues wrote in the paper. That deeper structure sounds suspiciously like a tomb. “We believe that the continuity of the shallow structure and the deep large structure is important. From the survey results, we cannot determine the material causing the anomaly, but it may be a large subsurface archaeological structure.”