explorer Bertram Thomas had been approaching the southern edge of the Rub' al Khali ("The Empty Quarter"). It was Thomas' ambition to be the first European to cross the great sands but, as he began his camel journey, he was told by his Bedouin escorts of a lost city whose wicked people had attracted the wrath of God and had been destroyed. He found no trace of a lost city in the sands, but Thomas later related the story to T. E. Lawrence ("Lawrence of Arabia"), who regarded Ubar as the "Atlantis of the Sands". Thomas marked on a map the location of a track that was said to lead to the legendary lost city of Ubar and, although he intended to return to follow it, he was never able to. The story of a lost city in the sands became an explorer's fascination; a few wrote accounts of their travels that perpetuated the tale. T. E. Lawrence planned to search for the location of a lost city somewhere in the sands, telling a fellow traveller that he was convinced that the remains of an Arab civilization were to be found in the desert. He had been told that the Bedu had seen the ruins of the castles of King Ad in the region of Wabar. In his view the best way to explore the sands was by airship, but his plans never came to fruition. The English explorer Wilfred Thesiger visited the well at Shisr in the spring of 1946, "where the ruins of a crude stone fort on a rocky eminence marks the position of this famous well." He noted that some shards found there were possibly early Islamic. The well was the only permanent watering place in those parts and, being a necessary watering place for Bedouin raiders, had been the scene of many fierce encounters in the past, In March 1948, a geological party from Petroleum Development (Oman and Dhofar) Ltd, an associate company of the Iraq Petroleum Company, carried out a camel-borne survey of Dhofar province. Like Thesiger, the party approached Shisr from the south, along the Wadi Ghudun. Their first sight of Ash Shisur was a white cliff in the distance. As they drew closer, they could see that the cliff was in fact the wall of a ruined fort built above a large quarry-like cave, the entrance of which was obscured by a