An analysis of the major royal castles with special regard to their functions and strategic importance. The book presents an overall view of the royal castles of Denmark, based on analysis of both written and archaeological sources. It focuses on the various functions of the royal castles and how they were used in peace and war. During the turbulent 14th century control of these castles was a prerequisite for maintaining the monarch's authority and defending the kingdom against internal rebels as well as foreign enemies. New castles were erected and elder castles rebuilt all over the country, especially during the reign of king Erik Menved (1286-1319) and king Valdemar Atterdag (1340-1375). The development of castle-building is seen in close relation to the building traditions elsewhere in Europe. The book is profusely illustrated.