Mason City, Iowa, is seen as their most dramatic American design development of the decade. It is the largest collection of Prairie Style homes surrounding a natural setting. Mahony and Griffin married in 1911, a partnership that lasted 26 years. Mahony's watercolor perspectives of Griffins' design for Canberra, the new Australian capital, were instrumental in securing first prize in the international competition for the plan of the city. In 1914 the couple moved to Australia to oversee the building of Canberra. Mahony managed the Sydney office and was responsible for the design of their private commissions. In Australia, Mahony and Griffin was introduced to Anthroposophy and the ideas of Rudolf Steiner which they embraced enthusiastically, and in Sydney they joined the Anthroposophy Society. In Australia, they pioneered the Knitlock construction method, inexactly emulated by Wright in his California textile block houses of the 1920s. Walter was asked to create a design for a library for the University of Lucknow in India, and went to the college in September 1935, and soon gained several other commissions. Marion arrived in April 1936, and soon took charge of the office, where she oversaw the design of many buildings. Less than a year later, in Feb 1937. Walter died of peritonitis following a cholecystectomy. Mahony then wound up the office, leaving many projects unbuilt, and returned to Australia. Mahony and Griffin spread the Prairie Style to two continents, far from its origins. She credited Louis Sullivan as the impetus for the Prairie School philosophy. She thought Wright's habit of taking credit for the movement explained its early death in the United States. Death and legacy Marion Mahony Griffin did not stay long in Australia after Walter's death. By then in her late 60s, she returned to the United States and afterward was largely retired from her architectural career. "The one time she addressed the Illinois Society of Architects, she made no mention of her work, instead lectured the crowd on anthroposophy, a philosophy of spiritual knowledge developed by Rudolf Steiner." She did however spend the next twenty years working on a massive volume of 1400 pages and 650 illustrations detailing her and Walter's working lives, which she titled "The Magic of America", which has yet to be formally published in book form. A manuscript deposited at the Art Institute of Chicago in c1949 was digitized, and since 2007 has been available online. In 2006