The great pyramids of Giza are one of the world’s most enduring mysteries. We know a lot about them at this point, but not everything, and I imagine some believe we’ll never learn it all.

Especially when more mysteries, like an “anomaly” detected beneath them, keep popping up.

A team of researchers from Egypt and Japan were using ground penetrating radar and a technique known as electrical resistivity tomography (ERT) when they discovered two underground structures below a cemetery on the west side of the Great Pyramid.

They’re not sure what, but something is buried below the pyramidal tombs.

A study was published in Archaeological Prospection states the structures appear to be stacked atop one another. The shallowest is L-shaped and around 6 feet underground, measuring 33×49 feet.

The lower structure is smaller, with an area of 33×33 feet, but is around 33 feet below the surface.

The Western Cemetery, the site of the discovery, has always been part of the bigger mystery. The area that’s flat and empty has always led people to wonder if something might be buried beneath it.

The distinct shapes of the anomalies means they’re almost certainly human-made, but until they can excavate, there are only guesses as to what might be down there.

“We believe that the continuity of the shallow structure and the deep large structure is important.”

We’ll all stay tuned for more information.

Although if you ask me, we’ll likely just find more questions.

If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?