Since 1991, 50 odd cities have been added to the World Heritage Cities List which today comprises 123 cities. Here, each of these cities is the object of a brief study which situates it in time and space, identifies its major historical milestones and describes its essential urban landmarks and features. Are also presented the criteria behind the recognition of these cities, according to the recommendations made by the International Council on Monuments and Sites to the UNESCO's World Heritage Committee.