One of the two massive steel arches that will form the roof of the main Olympic stadium began sliding along rails toward its final position over the stadium yesterday. The western arch first moved 5 centimeters in a test and by night had moved about 5 meters. Today it is expected to move at 5 meters per hour, meaning that it may cover the total 71 meters by the end of the day if there are no unforeseen problems. Movement might have been minimal yesterday, but it was a giant step for harried Olympic organizers, who saw the most complicated and controversial part of the construction for the Athens Games moving into place. The roof became a symbol worldwide of Greece’s delays in preparing for the Games, although officials stress that Athens will be ready. «Today we won the first bet. From now on a great amount of work needs to be done for us to win the great bet which is to organize Olympic Games that will be unique, excellent and the safest ever,» said Alternate Culture Minister Fanni Palli-Petralia, who has day-to-day supervision of Olympic projects. «Today was Greece’s reply to all those who question our ability to organize these unique Games.» Her relief was related also to the fact that the International Olympic Committee’s Coordination Commission, which oversees the Games’ preparations, was due in Athens yesterday for an inspection. The IOC has said that if the roof appears not to be ready in time it will have to be scrapped. The company building the structure says it will be completed by the end of June. The roof is made of white steel and blue polycarbonated leaves. It is designed by award-winning Spanish architect Santiago Calatrava. Each arch weighs 8,500 tons. In order to save time because of the delay in sliding it into place, workers have already installed 20 percent of the polycarbonated leaves on the western arch. The eastern arch is expected to move 64 meters. It was not clear when this process would begin. Government and IOC officials, as well as well as Athens 2004 organizers will meet this afternoon to review progress. Yesterday Prime Minister Costas Karamanlis, who is also the culture minister, met with Palli-Petralia and Deputy Minister Petros Tatoulis.