This volume explores how imperial powers established and expanded their empires through decisions that were often based on exaggerated expectations and wishful thinking, rather than on reasoned and scientific policies. It explores these exaggerations through the concepts of El Dorado, utopias and dystopias – undertakings based on irrational perceived values – in case studies from across the sixteenth to the twentieth centuries, and incorporates imperial traditions including Scottish, British, French, German, Italian and American. Various colonial spaces are considered, from the Mediterranean, Middle East, Africa, Australia, Asia and the Americas, and in doing so, the contributors offer new insights into the nature of imperialism and colonial settlement.