As reported by Autosport, it is the Grandstand 'Luffield Complex Grandstand' and 'Silverstone Grandstand'. Both Grandstand will be placed in the area Luffield Complex and National Pits Straight.
With two Grandstand, then the Silverstone capacity increased more than 3,500 seats.
"We had a fantastic audience for three days, Great Britain Grand Prix event last year and interest this year is much greater," says managing director Richard Phillips.
"Adding capacity means giving more fans the opportunity to witness the spectacle, fascination, and the drama of Formula 1 at Silverstone," he continued.
Silverstone will host the ninth series of F1 this year, which will be held on July 9.