Chiseled out of pale pink sandstone, the ancient metropolis of Petra in Jordan's Jebel al-Madhbah mountains is an architectural and engineering marvel nonpareil. Carved more than 2,000 years ago by the Nabataeans, a nomadic Arab tribe, the breathtaking megalith boasts an abundance of awe-inspiring rock facades, formations, tombs and temples. You enter the UNESCO World Heritage Site through the "Siq," a narrow, winding gorge so steep you must crane your neck to see the sky. After about a kilometer, the gorge opens to reveal the massive "Treasury," one of Petra's most famous ruins. Rose-red Petra is stunning at night, when both the Siq and city are lined by thousands of candles, as well as during the golden glow of the late afternoon.