Eye-popping: Saudi prince unveils mirrored skyscraper eco-city

A futuristic Saudi megacity is to feature two skyscrapers extending across a swathe of desert and mountain terrain, according to the latest disclosures on the project by the kingdom's de facto ruler.

The parallel structures of mirror-encased skyscrapers extending over 170 kilometres (more than 100 miles), known collectively as The Line, form the heart of the Red Sea megacity NEOM, a plank of Crown Prince Mohammed bin Salman's bid to diversify the Gulf state's oil-dependent economy.

In a presentation, Prince Mohammed sketched out an even more ambitious vision, describing a car-free utopia that would become the planet's most liveable city "by far".

NEOM was once touted as a regional "Silicon Valley", a biotech and digital hub spread over 26,500 square kilometres (10,000 square miles). Now it's a vehicle for reimagining urban life on a footprint of just 34 square kilometres, and addressing what Prince Mohammed describes as "liveability and environmental crises".

Officials had earlier said NEOM's population would top one million, but Prince Mohammed said the number would actually hit 1.2 million by 2030 before climbing to nine million by 2045.

The eye-popping total is part of a hoped-for nationwide population boom that Prince Mohammed said would be necessary to make Saudi Arabia, the world's biggest crude exporter, an economic powerhouse. The goal for 2030 is to have 50 million people -- half Saudis and half foreigners -- living in the kingdom, up from roughly 34 million today. By 2040 the target is 100 million people, he said.