Boasting its own artificial sun and a floor area three times that of the Pentagon, the “world’s largest building” has opened in southwest China to mixed reviews from its first visitors.

The towering 100-metre (330-foot) high New Century Global Centre, which is said to be big enough to hold 20 Sydney Opera Houses, recently opened its doors Chengdu.

The complex, which Chinese officials say is the world’s largest standalone structure, is 500 meters long by 400 meters wide, offering 1.7 million square meters of floor space.

But the first wave of visitors were divided over the attractions of the structure, which houses 400,000 square meters of shopping space, offices, conference rooms, a university complex, two commercial centers, two five star hotels, and an IMAX cinema.

The Global Centre has a marine theme, with fountains, a huge water park and an artificial beach, accented by the undulating roof, meant to resemble a wave.

The centerpiece is a 5,000 square meter artificial beach, which includes a rafting course and a “seafront” promenade, complete with parasols and seafood outlets that can accommodate 6,000 people.