Premier global construction company, Multiplex, has reached completion on the fifth and final commercial office tower at Walker Corporation's landmark $2.5 billion Collins Square development located at 727 Collins Street in Melbourne's CBD.

Collins Square is one of the largest commercial mixed-use developments in Australia. Spanning an entire city block, it consists of five commercial office buildings with retail space providing a combined total of more than 250,000 square metres of commercial space and 10,000 square meters of retail area.

The final $168.5 million tower spans 33-levels and reaches 117 metres in height. It provides a total area of approximately 40,000 square metres of commercial office space, and includes an integrated fit-out for the anchor tenant Transurban on Levels 24 – 31.

Designed by high-profile architects Woods Bagot, Collins Square Tower 5 features high quality office space with an architectural curved curtain wall façade to provide a light-filled spacious office floor plate. Tower 5 connects to the foyers of the adjacent towers and sits above retail, public circulation spaces, car parking and end of trip facilities.

"We are proud to deliver the final tower at Collins Square, completing this premier commercial precinct for Melbourne," said Graham Cottam, Regional Managing Director of Multiplex Victoria.

"The smooth delivery of this major project is a reflection of our on-going collaboration with Walker Corporation, which has seen Multiplex deliver the last four towers at Collins Square."

Challenges faced during construction include the construction of the tower above a seven level operational commercial carpark, and structural and service integration with the adjacent Tower 4 without interruption to existing tenants.

Innovative design features include a curved architectural curtain wall system and curved structural steel roof to prevent overshading of Southbank.

The building also includes innovative destination-controlled lifts with Bluetooth technology throughout allowing occupants to access and control the elevators via mobile phones.

Work commenced on Tower 5 in April, 2017 and according to Multiplex a total of 1,973 people worked on site throughout construction.

Collins Square seamlessly integrates commercial office space with retail on Collins Street. The precinct forms a vital 'bridge' between Melbourne's two major commercial centres, the CBD and Western Precinct.

The revival of Collins Square commenced in 2010 and includes the refurbishment of the historic Goods Shed which has stood at Melbourne Docklands for over 120 years. The precinct also includes innovative retail and dining space, as well as a childcare facility, supermarket, health and wellbeing and general services.

The Collins Square development has a Green Star Design and As Built v3 Rating as well as a minimum NABERS Energy 5 Star Rating due to its use of a Tri-Generation system for producing power; along with the rainwater harvesting system and water efficient fixtures and fittings. The precinct boasts the highest concentration of environmentally sustainable buildings in the Southern Hemisphere.

Multiplex has completed a number of commercial projects across Melbourne over the past few years including Cbus Properties Medibank office at 720 Bourke Street, National Australia Bank building at 700 Bourke Street and Queensland Investment Corporations development in Collins Street.