A TOTAL of 28 buildings, which will be the headquarters of some top state-owned companies, have been completed at the former 2010 World Expo site, the city government said yesterday. This is part of a redevelopment project on the former Expo area. Former Zone B Expo site will house 15 state-owned companies including Baosteel and State Grid. The projects will feature a super massive underground complex and a public space featuring environmental friendly materials above the ground.