It's twice as large as an Olympic-size swimming pool and almost as long, yet for thousands of years this massive ancient monument remained hidden in plain sight at a popular tourist spot.
The huge man-made stone platform was recently discovered with the aid of Google Earth and drones, laying under the sand within the "lost city" of Petra in Jordan. The find was detailed in a study published in the Bulletin of the American Schools of Oriental Research.
It's a particularly surprising discovery seeing as Petra is such a well-surveyed archaeological sight, full of tombs and monuments carved some 2000 years ago by the Nabataeans. Yet it shows there are significant structures that remain undiscovered in the area.
Due to its monumental staircase and columns constructed on one side, it's believed the platform may have been used for ceremonial purposes. Measuring 56m by 49m, a natural plateau would have been levelled in order to build it.
"It's this very large platform that many of us (archaeologists) have walked over for years, and probably didn't even realise we were walking on it," Christopher A. Tuttle, executive director of the Council of American Overseas Research Centers, said. Tuttle, who has worked at Petra for around a decade, collaborated with Sarah Parcak from the University of Alabama at Birmingham on the study.
"I'm sure that over the course of two centuries of research [in Petra], someone had to know [this site] was there, but it's never been systematically studied or written up."
There's also a second, smaller platform built on top of the first which was paved with flagstones and includes a smaller structure on top - believed to include a doorstep. Pottery was also found at the site, ranging in age.
However much will remain unknown about the structure until it's excavated, and there are currently no plans to do so due to the risk of damaging the site due to exposure to the elements.
Petra was declared a UNESCO World Heritage site in 1985, and some scenes from the movie Indiana Jones and the Last Crusade were filmed here. Once a thriving trade centre and the capital of the Nabataean empire, the city was later lost to the world for hundreds of years and sat empty.
Sadly, many of the city's tombs were looted by thieves and treasures were lost. Regardless, it remains the site of much intrigue to this day.