Two young Sydney architects have won an architecture competition to design a library and plaza as part of a €6.2bn ($8bn) redevelopment project in Australia. The €30m ($40m) library and plaza scheme will form the centrepiece of the Green Square renewal project, situated 4km south of Sydney. Felicity Stewart and Matthias Hollenstein, of firm Stewart Hollenstein, in collaboration with Colin Stewart Architects, were chosen last Monday as the winners of the City of Sydney design competition which saw 167 entrants from 29 countries.

The design includes a 3,000 sq m underground library connected to the plaza, together with a sunken story-telling garden, an amphitheatre and music rooms. According to the City of Sydney, a local government authority, “the Stewart Hollenstein design redefines the traditional idea of a library, fusing a range of innovative buildings with the outdoor plaza to create multiple sites for play, work and rest.”

With both architects in their twenties, winning the prize represents a huge boost to their fledging firm, which they have both been running part-time since 2010. The proposal was chosen by a group of Australian and international architects, including Glenn Murcutt, winner of the 2002 Pritzker Prize, with the winning proposal the topic of the City of Sydney Design Excellence Forum, which will be hosted this evening (4 March).