The sandstone Monastery and Treasury Building of Petra, carved by the Nabataeans nearly 2,000 years ago, astonish hundreds of thousands of tourists who visit southern Jordan each year. Unbeknownst to them, another enormous monument has been "hiding in plain sight" half a mile away. Satellite and drone imagery and ground surveys have revealed a platform as long as an Olympic-size swimming pool and twice as wide buried beneath the sand at the World Heritage site, reports National Geographic. Inside sat a smaller platform that would have housed a 28-by-28-foot building facing a staircase that study author Christopher Tuttle calls "fascinating," per the Guardian; the staircase is atypical in that it does not face the heart of Petra. "I find it interesting that such a monumental feature doesn’t have a visible relationship to the city," he says.
He says archaeologists previously suspected something was at the location of his find, but "the structure's sides resembled terrace walls common to the city" and so were seemingly ignored. Pottery found on the surface suggests the structure may date to about 150BC—or Petra's first glory age, per the BBC. Many of Petra's most iconic structures were built later, from the end of the first century BC to the second century AD. The city was eventually abandoned in the seventh century AD, rediscovered in 1812, and named one of the 7 new wonders of the world in 2007. No excavations are scheduled, but co-author Sarah Parcak notes satellite surveys of sites elsewhere in the world are underway. Expect "some pretty amazing discoveries over the next year," she says. (Archaeologists may have found a long-sought Aztec tomb.)