Conceived in the tradition of Thames-side palaces facing the river, the building integrates the disparate buildings of the Parliamentary estate. The accommodation is arranged in a six storey rectangular block, around a central courtyard. This is roofed at ground floor level by a diagrid of oak members with stainless steel joints, covered by a frameless glass skin. Surrounded by restaurants and the library, with shady trees and tranquil pools, it has become a meeting place and focus for Parliamentary life. The first floor gallery overlooking the courtyard gives access to a range of Select Committee Rooms. Above, there are five floors of MP's offices with views out either side over the courtyard roof or to the surrounding streets and river embankment. The building structure had to be co-ordinated with the Westminster Underground Station below. The inner walls around the courtyard are supported on only six columns, tied by a transfer structure of concrete arches. Gullwing precast concrete floor units span onto the perimeter walls of sandstone piers. Welded box girders, doubling as air ducts, form spider-like roof frames on top of the piers. The chimneys are the terminals of a sophisticated, energy efficient, ventilation system.