of Manchester city centre, to regenerate a 20-acre site with office, retail, residential and hotel space to encourage visitors from the city centre. Manchester City Council contributed £20m to the project as an incentive for redevelopment. In December 2011, the Co-operative announced its new headquarters would be known as One Angel Square. Construction Construction work began in July 2010 soon after planning permission was granted. The first task was installing the 539 pile foundations - each at an average depth of 18 metres. Work soon began on assembling the 3,300 tonnes of steel and 1,948 coffered concrete floor slabs which make up the structure of the building. BAM Construction was the main building contractor with cost management, project management and CDM coordination provided by Gardiner & Theobald. Specialist services were supplied by Buro Happold for structural and fire engineering and Austrian-based Waagner Biro was commissioned to build the double skin façade. The structure was digitally modelled by BAM before commencing assembly and construction to improve safety and create a building schedule thus saving time during the construction process. More than 4,000 workers from over 90 companies were involved in the building's construction making it the largest building site outside South East England. The building was topped out in November 2011 and work began assembling the bronze-coloured diagonal panels of exterior façade. The panels were installed using roped access techniques. An estimated £17m of building materials out of the total £100m cost has been locally sourced reducing embodied energy and minimising environmental impact. Mecanoo and Manchester-based Royal Haskoning designed the landscape in front of the building. Inauguration and opening Construction and fitting out was originally scheduled for completion in September 2012, however opening was postponed to 2013 due to delays in the fitting out process. In July 2012, the Co-operative Group announced One Angel Square was on the market for £150 million on leaseback terms so it could gain capital to invest in Phase Two of the NOMA development. The leaseback sale attracted nine bids from six continents. In February 2013, the Group sold the building for £142 million to DWS and Gingko Tree Investments, an investment arm backed by the Chinese sovereign wealth fund. Architecture The Manchester division of 3DReid designed the building with a brief to create a green, landmark building for the city. The building's distinctive form was conceived in a notebook sketch by the lead architect for