I flew to Vientiane for a day and then caught another Lao Airways flight to Phonsavanh to head to the Plain of Jars. As my flight was delayed, my guide in Phonsavanh changed my itinerary. We drove to Site 1 on the Xieng Khouang plain in the Lao Highlands at the northern end of the Annamese Cordillera, the principal mountain range of Indochina. Site 1, contains over 250 jars of varying sizes.The jars are made of sedimentary rock, usually sandstone, but also granite, conglomerate or calcified coral. They are angular or round and some have disks that could be lids. They can weigh up to 14 short tons (13 metric tons) and range from 3 to 10 feet (1-3 meters) in height.The jars lie amidst thousands of unexploded bombs left behind by the Secret War in Laos in the 1960s. The large quantity of UXOs (unexploded ordinances), in particular cluster munitions, makes the area dangerous. Only sites 1, 2 and 3 are open to visitors.