Harbours are highly complex systems, in which ecological, logistical, economic, social, legal, military and religious subsystems overlap and influence one another. In order to be able to properly evaluate the full extent and depth of the phenomenon 'harbour', an attempt must be made to identify these subsystems and their implications for the development of the settlements. One aim is therefore to initiate an interdisciplinary comparative analysis that overcomes the various chronological hurdles and spatial limits and allows harbours to be understood as system-relevant components.

1. Establishment of a uniform terminology

Significant terminological ambiguities can be observed in the discussion of harbours, in both the German-speaking and the Anglo-Saxon worlds. This is because the archaeological categories for such features − especially in prehistoric and early-historic periods − have, so far, been inadequately defined. This has resulted in the implication that facilities used for totally different purposes are of the same nature. In the case of harbour structures, this can be seen in the use of the German term 'Landbrücke', or the English 'jetty'.

Almost every assemblage of remains of human activity in coastal areas is interpreted as traces of a landing place or harbour. This unreflecting approach means that, de facto, every site near the coast can be seen as a landing place, with no methodological support or firm definition. The establishment of a uniform terminology is therefore a fundamental and essential precondition for further studies. Only thus will comparisons of the 'harbour' phenomenon in a pan-European and diachronic context become possible.

2. Clarification of the interaction between topography and harbour construction

This permits a comparative analysis of basic questions regarding the classification and comprehension of harbours as an interface between the water and the land. Networks of waterways and their connection with the sea or ocean must be understood and analysed as maritime and/or inland-water determinants.

It would be desirable to have an assessment of the topographical context from a nautical point of view, e.g. as 'the enclosure of the sea within the land' (mentioned in the Allgemeines Wörterbuch der Marine − navy dictionary − of 1794) that ensures the protective function of the harbour for stationary vessels. The topography is obviously a decisive parameter in the choice of the location. At the same time, one has to ask why harbour facilities were also built in places with unfavourable natural conditions. The sometimes extreme effort required to build a harbour is reflected in artificial protective structures such as moles. Changing environmental conditions can also force structural changes to be made, or even cause the harbour to be abandoned. 

3. Evaluation of the implications of the environmental history

The environmental conditions prevailing in each case, and changes in these conditions, are decisive factors in the establishment of harbours. Large-scale tectonic uplift and subsidence, silting up or drying out, changes in the course of rivers − are all phenomena that can occur to varying degrees. The resulting changes in the water level demanded new technical solutions for the continued operation of the harbours: the economic success and even the existence of a port or maritime trading place depended on the effectiveness of the solutions found. They may even have had to be abandoned if the available technical resources were not equal to extreme environmental changes.

Changing environmental conditions are therefore fundamental factors in understanding both individual developments and demonstrable supraregional changes. Here, aim of the SPP is to identify the strategies used to deal with dynamic environmental processes, by means of comparative analyses in various cultural regions. 

4. Analysis of economic and transportation areas

Harbour towns have a unique position as relay stations between the terrestrial and maritime spheres. They alone act as a link between two basically closed networks. Harbours are therefore logistical hubs in the supraregional, regional and local production and distribution infrastructure. Their economic significance lies in their central role in the transshipment of goods. The utilization of resources near the water, the procurement of local raw materials and local production are equally important, as is the link between central marketplaces and the maritime trading places and port settlements with their supraregional orientation.

A further aim of the SPP is to be able to interpret the economic role of harbours in relation to their links with the transportation routes. This is to be accomplished by a comparative analysis of archaeological features, selected groups of finds and historical sources. As the places where goods are transshipped, their role in regional and long-distance trading networks has to be determined and a foundation laid for comparative synchronic and diachronic studies.

5. Generation of a model of historical and cultural development

By examining the individual fields of study described above − terminology, interaction between topography and harbour construction, environmental implications and the analysis of the economic and transportation areas − it is hoped that a comprehensive evaluation against the background of regional and supraregional cultural traditions will become possible. An analysis of regional and chronological similarities and differences between the Mediterranean area and northern and central Europe, and between the Roman period and the Middle Ages, will thus lay the foundation for the creation of generic development models.