At a time when the whole of Europe is growing ever more united, the study of cultural phenomena observable all over the continent gains in importance. One such phenomenon is the occurrence of earthworks of both prehistoric and historical date. Initially associated with tribal Europe and with that period of its history when early states began to emerge, these defensive features began to decline with progressing feudalization. Within Latin Europe they were replaced by imperial ‘pfalze’, feudal seats of the motte type, and castles. Built by rulers, ecclesiastical dignitaries and knights all over the area stretching from the Atlantic Ocean to Russia, they were the most outstanding feature of the cultural landscape of medieval Europe. With the decline of the Middle Ages, changes began to affect those castles that were built on an extensive scale as well as smaller defensive features such as the keep on a mound. The picture of European defensive architecture also changed under modern cultural influences from transalpine Italy. One trend led towards ‘military architecture’ in the narrow sense of the word. Modern fortifications became the concern of specialists: engineers and practicians of the battlefield in the period termed by Michael Howard the era ‘of wars of mercenaries, merchants and professionals’ (1976). The other trend was to shape modern civilian architecture, in terms of the development unfortified palaces. The division between architectura civilis and architectura militaris became a fact.