City Hall, Southwark, London, England. City Hall houses the assembly chamber for the London Assembly and the offices of the Mayor of London and the Greater London Authority. It is situated on the south bank of the River Thames. The design of City Hall was aided by computer modelling techniques which enabled its advanced energy- saving design features. The unusual modified sphere shape minimises exposure to direct sunlight creating optimal energy exchange. The south of the building (right) leans back so that its floor plates jut outwards, creating shade for the offices below. Parts of the building are open to the public. It was completed in late December 2001.