The first of 14 lighting towers has been lifted into place at the London 2012 Olympic Stadium, taking the venue to its full height of 60m above the field of play.
A 650t crane was used to lift the 28m lighting tower, which will illuminate the field and offer various lighting angles.
The scheme is expected to be complete in 2011, the Olympic Delivery Authority (ODA) said.
ODA chairman John Armitt said the lifting of the lighting towers was a significant engineering and construction challenge.
A total of 14 lighting towers, each weighing 34t, will be placed on the roof. They will feature integrated walkways, access, power supplies and cabling and lighting.
The cable-net roof of the stadium will be covered with material once all the lighting towers are in place.