© 2015 Taylor & Francis. In 1912, Walter Burley Griffin famously won the international design competition for Australia's national capital, later named Canberra. In 1914, Walter – along with his wife and professional partner Marion Mahony Griffin – moved from their native Chicago to Australia to orchestrate Canberra's realization. On a return visit to the USA in 1925, Walter was commissioned to lay out an extension to the Chicago suburb of Park Ridge. Until now, this project was only known from a singular, passing mention of it in a period newspaper article. This report reconstructs the writer's convoluted effort – spanning more than a decade – to confirm Walter Burley Griffin's authorship of this enigmatic project and to locate the plan itself. In parallel, it recovers, partly based upon evidence-derived suppositions, the circumstances surrounding what proved to be Griffin's final American commission.