PETRA IS ALREADY ONE OF THE MOST beautiful and mystifying places in the world, but the Jordanian heritage site just got a little bit more mysterious. Archaeologists, using satellite and drone imagery, have discovered a new monument that’s approximately the size of an Olympic swimming pool “hiding in plain sight.”

The finding is part of a relatively new trend in archaeology that uses satellite imagery and drone photography (coupled with the more typical surveying techniques) to identify underground historical sites that are hard to see from level ground, but are much easier to make out from above. Christopher Tuttle, one of the archaeologists that discovered the new monument, believes that some other excavator or archaeologist had to have known about the site at some point, but must not have made any note of it.

Massive New Monument Found by satellite & drone in Petra :: https://t.co/jxULDsMMdo pic.twitter.com/2xdsj50dNa — DroneLabs (@DroneIndustries) June 10, 2016

The aerial photography makes it much easier to see small depressions in the landscape that might not be immediately obvious to the naked eye. The researchers believe the platform likely held some sort of ceremonial significance, and it was built during the city’s peak in the second century, BC.

This was a fairly high-tech archaeological operation, but it turns out anyone can participate in making similar discoveries. Archaeologists are always trying to find new sites to dig at, but there’s so much satellite imagery that they simply don’t have the manpower to look through all of the images. So lately, they’ve been crowdsourcing the work. Sarah Parcak calls herself a “Space Archaeologist,” and set up a platform called Global Xplorer that allows anyone to look through satellite imagery and find the tell-tale signs of an underground city or temple. Parcak even made sure that people given the images aren’t given the exact GPS coordinates, to ensure that terrorist groups like ISIS (who are not too far away from Petra) can’t use the information to loot historical sites for ransom. It’s part of a greater attempt to “game-ify” archaeology in order to make more discoveries about our past as humans. For her work, Parcak has become a National Geographic Fellow and won the 2016 TED Prize.

Parcak was the other researcher behind the discovery of this new site. And if the discovery at Petra shows us anything, it’s that even the most well-trod archaeological sites still hold secrets. Indiana Jones is cool and all, but today’s archaeologists are way more high tech, and if Parcak and Tuttle are any indication, may be even cooler.

For more information, check out National Geographic and the BBC.