BBC: "I've worked in Petra for 20 years, and I knew that something was there, but it's certainly legitimate to call this a discovery." via National Geographic
'Mr [Christopher] Tuttle told National Geographic that someone in decades of excavation "had to know" the structure was there yet it had not been written up.
'Archaeologists used satellite images, drone photography and ground surveys to locate the find, according to the study published in the American Schools of Oriental Research. The large platform is about as long as an Olympic swimming pool and twice as wide. Researchers say it is unlike any other structure at the ancient site.'
"Hiding in Plain Sight: The Discovery of a New Monumental Structure at Petra, Jordan, Using WorldView-1 and WorldView-2 Satellite Imagery" by Sarah Parcak and Christopher A. Tuttle here