PETRA   -   At the heart of the an­cient city of Petra, Jor­dan, carved into pink sandstone cliffs, lies an elaborate monument known as the Khaznah, or the Treasury. And buried beneath that edifice, archaeologists recently discovered, is a tomb with at least 12 human skeletons and artifacts that are es­timated to be at least 2,000 years old. Ar­chaeologists led by Dr Pearce Paul Creasman, executive director of the American Center of Re­search, unearthed the ancient tomb. The ex­pedition was studying the Treasury after years of speculation that two tombs found below the left side of the monu­ment in 2003 weren’t the only secret under­ground chambers. But that theory had not been confirmed — until now. Creasman and his team performed ground-pen­etrating radar — a re­mote sensing technique that uses radar pulses to detect underground objects — earlier this year to see whether the physical features on the left, where the origi­nal tombs were found, matched those on the right. The detections revealed strong simi­larities among the two sides, and it was the proof they needed to re­ceive permission from the Jordanian govern­ment to dig beneath the Treasury.