Vienna, Austria's grand capital on the Danube river, has topped consulting firm Mercer's list of cities offering the highest quality of life for the eighth year in a row, while Baghdad is again considered the worst place to live. The survey of 231 cities helps companies and organizations determine compensation and hardship allowances for international staff. It uses dozens of criteria such as political stability, health care, education, crime, recreation and transport. Global centers London, Paris, Tokyo and New York City did not even make the top 30, lagging behind most big German, Scandinavian, Canadian, New Zealand and Australian cities. Singapore was the highest ranked Asian city, at 25 while 29th-placed San Francisco was the United States' highest entry. Top of the list in Africa was South Africa's Durban at 87. Vienna's 1.8 million inhabitants benefit from the city's cafe culture and museums, theaters and operas. Rents and public transport costs in the city, whose architecture is marked by its past as the center of the Habsburg empire, are cheap compared with other western capitals. Switzerland's Zurich, New Zealand's Auckland, Germany's Munich and Canada's Vancouver followed Vienna in the top five of most pleasant cities to live in. Baghdad was again ranked lowest in the world. Waves of sectarian violence have swept through the Iraqi capital since the U.S.-led invasion in 2003. Six years into Syria's bloody war, Damascus was ranked seventh from bottom, with Bangui in the Central African Republic, Yemeni capital Sanaa, Haiti's Port-au-Prince, Sudan's Khartoum and Chad's N'Djamena filling out the end of the list.