In 2017, the Bonlieu Cooperative for Housing and Culture in Zurich celebrates its 100th anniversary. Founded as Free Youth Uster, it soon operated under the name Proletarian Youth Zurich. From the very beginning, it provided living and recreational space for young people. In 1928, the legendary youth home Sihlfeld was inaugurated in Zurich, which became an important meeting point for the European labor movement, and whose building, along with the restaurant "Café Boy," still belongs to the cooperative today. This book tells the story of the cooperative, its protagonists, and the changes it has undergone over the past 100 years. A dedicated chapter is devoted to its built manifesto, the building of the Workers' Youth Home Sihlfeld, placing it within the broader context of architectural and social history.