This week marks the 50th anniversary of the treaty bringing hundreds of thousands of Turkish "guest workers" to Germany, a move which dramatically altered the fabric of German society.
On October 30, 1961, booming West Germany signed a recruitment agreement with Turkey to supplement its workforce. The mostly unskilled labourers were promised minimum wages and accommodation for the duration of their temporary contracts.
Some 710,000 people answered the call until the 1973 global oil crisis ended the recruitment drive. Thousands of workers returned to Turkey, but many instead decided to bring their families to Germany, triggering a massive increase in the country's Turkish population.