Athens Olympics organisers have to solve dilemmas concerning the roofs at three key stadia before the Games get under way this summer, it has emerged.
Two giant interlocking steel booms have been erected outside each end of the Olympic Stadium and the plan is to slide them towards each other, leaving a gap in between, and then hang two roof wings from the structure.
Steel and glass panels, designed by Spanish architect Santiago Calatrava, will be hung from wiring attached to the booms creating shelter for spectators. The process of sliding the booms into position is expected to take up to 10 days.
Meanwhile, organisers will decide later this week whether or not they can provide a temporary roof for the outdoor Olympic swimming pool in time for the start of the Games.
A roof is needed by the swimmers to protect them from the effects of intense heat and by the broadcasters to reduce the glare factor from the sun.
The final roof problem within the Olympic Sports Complex, which will host opening and closing ceremonies, athletics, swimming, basketball, gymnastics, tennis and cycling, concerns the roof for the cycling velodrome.
Constructors have built the roof before laying the cycling track and must now decide whether to lay the track and slide the roof above it or slide the roof into position and then lay the track.