On Wednesday night, German archaeologist Till F. Sonnemann addressed a gathering at the Ecole Francaise d’Extreme Orient, and claimed he has used ground-penetrating radar (GPR) technology to discover multiple Angkorian tower foundations that were previously unknown of.

The GPR machine, which looks like a lawn mower, sends radar signals into the ground where they detect differences in density or electromagnetic properties.

“It’s like the same type of technology that you would use on a plane. The processing unit of the machine calculates the time it takes the radar to bounce back so we can measure distances of anomalies in the ground,” says Sonnemann, a 31-year-old PhD candidate at the University of Sydney. Those anomalies can be substances like metal or sandstone that were used in Angkorian structures.

Whether the towers were ever actually built remains a mystery, but Sonnemann claims he has discovered at least six, possibly eight, of the structures.

He also claimed that it’s the first time that GPR surveys have been used at Angkor on a major scale. Over three field seasons, the surveys have revealed ancient riverbeds and engineered channels. “I’m running around the countryside with the GPR machine trying to figure these things out,” says Sonnemann.

Sonnemann has also surveyed the great Angkor barays and says he’s discovered a new outlet on the eastern side of Indratataka Baray. He’s also come across a few areas that may have been outlets. “We’re not sure yet though. All we know is that there’s laterite floor where the outlet should be.”