Contractors at Wembley last week began to lift the 1,750t steel arch, which is now standing at 20infinity to the horizontal. Turning struts are rolling the arch up into the air using 10 sets of cables. The pencil shaped ends of the arch are pin jointed, allowing it to rotate. Initially the arch was lifted just off the ground and left hanging for a week so that it could be surveyed and monitored. Paintwork was touched up and the temporary supports removed. Contractor Cleveland Bridge began the lift in earnest last Friday. 'It is the biggest prefabricated roll up lift ever attempted, ' said a spokesman for the project. Upon completion the arch will span 315m and stand 133m above ground level, making it the largest single span roof structure in the world (NCE 15 January).