President Obama toured the ancient city of Petra Saturday as he ended a trip to the Middle East in Jordan, where he pledged more U.S. aid to Syrian refugees. Jordan\'s most popular tourist spot was cleared of other visitors as the president strolled the 2,000-year-old city carved from a rocky cliff, the final stop on his four days of travels. Dr. Suleiman A.D. Al Farajat, a tourism professor at the University of Jordan, led Obama on the tour. His casual tour contrasted with his hectic schedule of the previous days. While most of the time was spent in Israel, where the president talked to Prime Minister Binyamin Netanyahu, he also traveled to the West Bank to meet with Mahmoud Abbas, president of the Palestinian Authority. King Abdullah II welcomed the president to Jordan late Friday, telling Obama he was looking forward to an \"Arab Summer.\" At a joint news conference, the king said Jordan would continue to provide shelter for Syrian refugees and to do whatever it can to facilitate talks between Israel and the Palestinians. Obama pledged the U.S. would provide another $200 million in aid to help those who have fled the nearly two-year-old conflict. Abdullah spoke of the strain recent events are putting on Jordan, describing the Zaatari refugee camp as the country\'s fifth-largest city. But he said there is a \"window of opportunity\" to reshape the Middle East that could close quickly. \"This is the Jordanian moment. What we\'re seeing is the third way in the Middle East -- we are seeing that the Arab Spring is behind us; we in Jordan are looking now at the Arab Summer for us all, which means that we all have to roll our sleeves,\" he said. \"It\'s going to be a bumpy and difficult road, but I am very encouraged with the process and I am very excited about the future.\" Obama described Jordan as an \"invaluable ally\" and a \"great friend.\"