Saudi Arabia is planning the world’s largest buildings in a mostly unpopulated part of the country as part of an entirely new $500 billion development called Neom, according to people familiar with the matter.

Neom, the brainchild of Saudi Crown Prince and de facto ruler Mohammed bin Salman, aims to build twin skyscrapers about 500 meters (1,640 feet) tall that stretch horizontally for dozens of miles, the people said. 

The skyscrapers would house a mix of residential, retail and office space running from the Red Sea coast into the desert, the people said, asking not to be identified as the information is private. The plan is a shift from the concept announced last year of building a string of developments linked by underground hyper-speed rail, into a long continuous structure, the people said.

Designers were instructed to work on a half mile-long prototype, current and former Neom employees said. If it goes forward in full, each structure would be larger than the world’s current biggest buildings, most of which are factories or malls rather than residential communities.

Announced in 2017, Neom is Prince Mohammed’s plan to turn a remote region of the country into a high-tech semi-autonomous state that re-imagines urban life. It’s part of his plans to attract foreign investment and help diversify the Saudi economy away from a reliance on oil sales. The Line, as the car-free linear city that will form the backbone of Neom is known, could cost up to $200 billion to build, the prince said last year, though that was before the plan changed to include gigantic horizontal buildings. 

Keep reading on Bloomberg.com