玛甸沙勒（也被称为黑格拉）的纳巴泰墓，沙特阿拉伯 Nabatean tomb in Mada'in Saleh (aka Hegra), Saudi Arabia (© Tuul & Bruno Morandi/Getty Images)
孤独的城堡 The lonely castle
Mada'in Saleh, Saudi Arabia
About 2,000 years ago, Mada'in Saleh, or Hegra as the Romans called it, was a thriving city of the Nabataean Kingdom, and a center for the trade of spices, incense, and myrrh, a valuable tree resin used to make perfume and medicine. The Nabataeans were Arab people whose precise origins are unknown. They lived in northern Arabia and the Southern Levant. Mada'in Saleh was their second-largest and southernmost city after Petra, their capital city to the north. About halfway between Petra and Mecca, Mada'in Saleh served primarily as a trading crossroads and was instrumental in establishing the Nabataeans as prosperous middlemen to the rest of the ancient world.
Today it is one of Saudi Arabia's most celebrated historic treasures, and a UNESCO World Heritage Site, distinguished by more than 100 tombs with ornate facades, carved from sandstone outcroppings on the outskirts of the city. The smallest is less than 10 feet tall, the largest more than 60. Most of the tombs were carved in groups, but this especially embellished monument is relatively isolated, which is why today it's known as the Qasr al-Farid (the Lonely Castle). Here in this windswept desert the bustle of merchants and the caravans full of spices are long gone, but these hand-carved boulders rising abruptly out of the landscape remain as evidence of a time when all roads led to Hegra.