The United States lost its top-tier AAA credit rating from Standard & Poor's on Friday, hours after investors alarmed by the euro zone debt crisis forced Italy to speed up an austerity drive.
The world's biggest tower is to be built for $1.2billion in Saudi Arabia by the Bin Ladens.
Prince Alwaleed bin Talal said he had signed a deal to build the 3,280ft high Kingdom Tower north of the Red Sea city of Jeddah.