SHANGHAI - Work crews have completed the foundation for the world's second tallest building one month ahead of schedule and are now rushing to construct the ground structure of the 632-meter Shanghai Tower, second only to the 828-meter-tall Burj Khalifa in Dubai.

Located in China's financial hub of Shanghai, the building is expected to grow by 400 meters next year, with an average of seven days spent on the construction of each floor, said Kong Qingwei, board chairman of the development firm Shanghai Tower Construction and Development Co Ltd.

Kong said Wednesday that it took three years to complete the foundation, and he estimated it will take another three to finish the ground structure.

Once completed, the Shanghai Tower will be the tallest structure in China as well as a new Shanghai landmark alongside the 420.5-meter Jin Mao Tower and the 492-meter Shanghai World Financial Center. The three skyscrapers in Shanghai's Lujiazui Financial Zone will be connected by subways.

Kong said the Shanghai Tower will be a "vertical city" as it will house hotels, offices, malls and other facilities and will be capable of holding more than 50,000 people.