It is notable for its strong, square, black form, in late International Style modernism, and for a trade dispute which delayed the construction by a decade.

[2] Construction began in 1973, but was delayed in part by a labour demarcation dispute with the boilermakers trade union, who claimed the exclusive right of its members to weld the structural steel.

[10] Members of the BNZ development team travelled with Stephenson & Turner Architects to view architecture in the USA, Europe and Australia.

The building's imposing design has been criticised, with architect Sir Ian Athfield calling it "Darth Vader's pencil box".

[12] The seismic and wind-resisting frames of the building consist of a steel “tube” built around the perimeter of the tower connected via floor diaphragms to the stiffer central core.

The façade consists of precast concrete units faced with black Brazilian tijuca granite,[14][10] with black-glazed windows built into them.

The food court area was remodelled and reopened in 2023 as a new entertainment venue called Willis Lane, which includes a mini-golf course, bowling alley and various bars and eating places.