Singapore's skyline of the future took shape within the National Stadium yesterday, in the form of a "sky city" that hovered in the air.

In an other-worldly sequence, 15 clusters of buildings, including iconic landmarks such as the Changi control tower, the Esplanade and Gardens by the Bay, floated up above the stage as performers in glimmering outfits glided across on electric personal mobility devices, bathing the scene in a luminescent blue.

The song Rise, composed and sung by local songwriter Don Richmond, gave the scene an ethereal atmosphere, with pulsing opening beats that segued into warm, soothing vocals.

Mr Kenny Wong, 49, the show's technical director, said the segment was inspired by discussions after the SG50 celebrations last year.

"There were loads of speculations about the future city, and what Singapore will be like. One of them was a floating city, which caught the imagination of the creative team," he said.

The team had to work within the confines of the stadium, figuring out how a sky city could be attached to the roof, "which can hold only a certain amount of weight", he added. It took nine months to design the sky city, the most challenging and elaborate set of aerial props in the show.

Another two months were required to construct the props, which are made from lightweight aluminium and wrapped in fabric.

Each cluster of buildings weighed about 250kg to 340kg. They were loaded onto carts that needed to be pushed into position before the act.

The props were then attached to the aerial system, which had been rigged up to the stadium's domed roof to support their movement.

Full-time national serviceman Yap Te Rong, 20, one of the show management ground personnel, said that coordination was crucial.

As the movement of the hoists on the aerial system run on preset timings, they had to attach the aerial props in time lest the hoist lifted up into the air without a prop attached.

"You won't have another chance, and you will spoil the show," he said.

They also had to be mindful and keep clear of the trapdoors - three of them opened during this sequence for other building clusters to rise up.

But all the effort was worth it for Mr Yap when he saw the sky city come together amid the cheers of the crowd and the sparkling lights in the stadium.

"It's quite an amazing feeling. It's a fascinating, futuristic show."