evidence: In the Syrian Desert, about 80 Km. south-west of Palmyra, lies Qasr al-Hayr al-Gharbi. It is constructed in an oasis watered from a valley feeding it during the rain seasons. Its location is remarkable for being situated at the cross-roads of two important routes of the Desert: The route of Damascus-Qaryatayn Palmyra, and the route of Homs-al-Jawf both are old routes linking together the two wings of the Fertile Crescent. Qasr al-Hayr al-Gharbi is one of the many palaces built by the Umayyad Caliphs and Princes in the Syrian Desert and Jordan. Among these Palaces are: Qasr al-Hayr ash-Sharqi (100 Km. north-east of Palmyra): the Arab Palaces of ar-Rusafah, constructed outside the ancient Byzantine city of Sergiopolis: the Palace of Wasit ar-Raqqah ( on the west bank of the Euphrates); Jabal Usays (100 Km. east of Damascus); the Palace of Hisham (Khirbat al-Mafjir near Jericho of Jordan); al-Mushatta; Qusayr Amrah; and Khurranah... The last three palaces are situated in Transjordan. [...] Qasr al-Hayr al-Gharbi is almost square; its side being 70 meters. It is supported by cylindrical towers at the corners and semi-cylindrical towers on the walls and on either side of the door which opens on the eastern side.