second, or even third, year. Students are not obliged to leave the college at the end of their first year. Returners play a role in setting the tone of the college, passing on traditions, and making incoming students feel welcome. In recent years, the male:female ratio has approximated 40:60, which is reflective of the male:female student ratio throughout the university. Centennial celebrations The college achieved its centenary in 2009, with approximately 600 guests attending a variety of events over the celebration weekend in early August. The oldest returning resident (res. 1938–1943) planted a Centennial Oak in the college grounds to commemorate the occasion. Relationships with other colleges Knox College shares its site with Salmond College. Although the two colleges are mostly autonomous in regards to their daily operations, they are governed by the same body, the Board of Knox College and Salmond College, and, being part of the same organisation, they share several staff, including an Operations Manager, a Food Services Manager, a Property Manager and a Groundsman. Knox College enjoys a close relationship with its Anglican equivalent and arch-rival Selwyn College. The two colleges compete annually for the Nevill Cup (cultural events) and Cameron Shield (sporting events). The eighth Master of Knox College, the Very Rev Dr Graham Redding (2015-2021), was a former Warden of Selwyn College (1989–1991). Building history The college buildings are an imposing group representing a persistent and successful effort to carry out an architectural idea over an extended time which saw considerable change. Initial outlay The Presbyterian Church of Otago and Southland opened a seminary for Ministers, its Theological Hall, in Dunedin in 1876. Early in the 20th century it acquired the core of the site in Opoho, above North East Valley, intending to re-house the seminary and to provide accommodation for its students and others attending the University of Otago. It established a brief and conducted an architectural competition won in 1906 by the 21-year old William Gray Young of Wellington. J. Louis Salmond (1868–1950) came second. Young's plans envisaged development well beyond the college's immediate requirements taking the form of four ranges surrounding a central quadrangle. After the first stage was completed he was retained as architectural adviser and remained responsible for the buildings' design for more than forty years. His successors remained true to his conception through challenging circumstances. The construction contract for the main accommodation block was won by Fletcher Brothers