Aon Centre (Wellington)

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Aon Centre
BNZ Tower.jpg
Aon Centre at 1 Willis Street
Former namesBNZ Centre, State Insurance building
General information
Architectural styleStructural Expressionism
Location1 Willis Street, Wellington, New Zealand
Coordinates41°17′12″S 174°46′35″E / 41.286741°S 174.776393°E / -41.286741; 174.776393
Construction started1973
OwnerPrecinct Properties New Zealand Ltd (formerly the AMP NZ Office Trust)
Height103 m (338 ft)
Technical details
Structural systemSteel moment frame
Floor count30 (3 below ground, 26 above)
Floor area26,892 m² (net lettable)
Design and construction
ArchitectStephenson & Turner Architects
Structural engineerBrickell, Moss, Rankine & Hill

The Aon Centre is a commercial office building at 1 Willis Street in Wellington, New Zealand, formerly named the BNZ Centre or the State Insurance Building. When completed in 1984, it was the tallest building in New Zealand, overtaking the 87m Quay Tower in Auckland. 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. It remained the tallest building in New Zealand until 1986, and is currently the second tallest building in Wellington after the Majestic Centre.


The building was designed in the late 1960s[1] and BNZ (Bank of New Zealand) began purchasing land for the building in 1969.[2] Approval to build was granted by the Town Planning Committee on June 14, 1972, after the building codes were rewritten to allow the development "out of common interest."[2] Construction began in 1973, but construction 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.[3] The dispute was characteristic of the time, disrupted construction for six years and discouraged construction of steel buildings across the country.[4] In response to the problem, the government of the day deregistered the boilermakers union.[citation needed] The dispute would lead the building to be four times over budget, ultimately costing $93 million.[4]

In 1979, the original building contract was terminated and a new contract to finish the building was signed in 1981.[3] The complex was completed and occupied in late 1984.[3] After the BNZ moved its head office to Auckland in 1998, State Insurance purchased the naming rights to the building, renaming it the State Insurance Tower.

In 2018, insurance brokerage Aon purchased the naming rights to the building, naming it the Aon Centre. Aon have been tenants in the building since 2013.[5]


This black on black building is one of the most striking office buildings in New Zealand. Wanting a “symbol of endeavour”, key members of the BNZ development team travelled with Stephenson & Turner Architects to study the best current high-rise thinking around the world, including major architectural centres of the USA, Europe and Australia.

Conceived as a sheer form of Zen-like simplicity, to be viewed across an open plaza, the building reflects Mies Van de Rohe’s iconic Tower Buildings (Lakeshore Drive Apartment Buildings in Chicago and Seagram Tower in New York), while also echoing the structural composition of the BHP Building in Melbourne by Yuncken Freeman (1967–1972). The latter, designed in Chicago under the tutelage of Skidmore, Owings & Merrill (key members of the team worked alongside Mies) to be Melbourne’s tallest and the most efficient use of steel in a high-rise building, reflecting BHP’s core business.

Misunderstood in design terms, and poorly labelled by many, the building’s subtle simplicity through careful material choice of black Brazilian tijuca granite and dark glass was an intentional expression of the highest levels of Modernism and thought through to a high level of detailing. The near flush façade was designed to deal with a number of conflicting elements including the building’s structural movements and the first fully automated BMU5 system in New Zealand.

Designed with a ductile steel frame, the building was to go up in record time. Construction commenced in 1974 but was held up for around nine years as a result of a political standoff between the Muldoon government and the Boilermakers Union. Ongoing strikes and go-slows eventually led to the union’s deregistration and to steel construction going out of favour in New Zealand for many years. The building was eventually completed in 1984 and now stands as a striking landmark on the Wellington CBD skyline.

Standing at 102 metres, with 30 floors, it was New Zealand’s tallest building from 1984 to 1991 when the Majestic Centre was completed on the same street. The tower is set in the middle of a wide plaza, offering opportunities for social and cultural activities at the busiest retail area in Wellington’s CBD. The bank has traded on this site since 1862.

Underneath the building is a shopping centre and food court. There are also underground passages that travel under Willis Street to the nearby Old Bank and Grand Arcades.

Above ground the tower is accessed by a grand, two-storey high lobby, surrounded by clear glass in stainless steel framework. The BNZ originally occupied three levels with their branch office, and the top seven floors with their head office. The uppermost executive floor featured impressive double-height office spaces panelled in native kauri. This level was connected to the floors below with the historical Beauchamp Stair, relocated from the Old BNZ Building. Because of its sheer size and steel construction the building is relatively flexible. Its response to frequent Wellington earthquakes is relatively good. Of greater effect is Wellington’s wind which is accommodated by the building’s ability to flex by up to 300 mm in hurricane-force winds. 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 building's design has been criticised, with architect Sir Ian Athfield calling it "Darth Vader's pencil box".[1]

See also[edit]


  1. ^ a b "Window falls from high rise". Stuff. Retrieved 2015-10-11.
  2. ^ a b Huggins, John (1986). "BNZ Building: Wellington as symbol and architecture". Architecture New Zealand (5): 11.
  3. ^ a b c Stephenson and Turner (1986). "BNZ Wellington". Architecture New Zealand (5): 25.
  4. ^ a b "A monument to militancy". Stuff. Retrieved 2015-10-11.
  5. ^ "Ex-BNZ & State Tower takes on third name - The Bob Dey Property Report". Ex-BNZ & State Tower takes on third name. Bob Dey Property Report. 28 March 2018. Retrieved 4 September 2018.

External links[edit]