For a deeper understanding of the relationship between a riverine settlement und a nearby river in the Early and High Middle Ages, some basic characteristics of inland navigation at this time have to be outlined. To examine the relevance of a river for a settlement or the cultural landscape of a specific period, first of all the river course in the corresponding time has to be clarified – but that could cause problems. To give an example, the Rhine river as well as other waterways has been corrected in the 19th and 20th century to fit the needs of inland navigation. Many traces of older natural courses of the river like meander loops are preserved until nowadays, but usually their chronology is unclear. Therefore, in addition to archaeology a strong geographic expertise is necessary to answer the question which course was active in the Early and High Middle Ages. An advantage of rivers is the comparatively easy way to transport heavy loads over long distances . The oldest and most ordinary media of transportation on early and high medieval inland waterways are logboats. A more advanced and very common type of inland water craft is the flat-bottomed boat. Wrecks of this kind dating back to the beginning of the 9th century have been found in Krefeld-Gellep and Bremen among other sites. An important detail of the complex construction is the arrangement of fore or aft in an obtuse angle, that allows for a landing on flat riverbanks without any constructions, which could therefore be labeled as “natural harbours” or hythes. This technical parameter is essential for the question how a riverine harbour or landing site in the Early and High Middle Ages had to be conditioned and if there have been a general need for artificial structures. From the 10th century onwards there is more and more archaeological proof for massive harbour constructions such as quays and jetties at European rivers and lakes, which make it possible to moor with waterlogged boats. An early example of a massive bank-parallel landing construction dating to the 10th century has been excavated in Konstanz at the Bodensee lake, in the 11th and 12th century this quay is complemented by additional jetties . Similar constructions have been used at rivers, which is documented by a 12th/13th century quay made of stone with additional wooden components at the northern bank of the Main in Frankfurt . Nevertheless, due to the possibility to land on natural harbours with most early and high medieval vessels, in many cases it was not necessary to build complex harbour constructions. Often some poles to tie ships, simple wooden bank stabilizations and a pavement made of stone or wood to facilitate the accessibility of the harbour have been sufficient . The major advantage of a “natural harbour” is the fact indeed, that in contrast to complex constructions hyhtes are much less vulnerable to hydrological and morphological transformations such as water level changes or the shifting of river courses. Furthermore, they are both easier to build and to maintain. The major disadvantage for archaeology is, that usually a “natural harbour” is very hard to identify, due to a lack of archaeological remains. The question of harbour construction and localization is therefore identical with the question of the nature of the river, its courses and its banks in a particular period. Furthermore, the interpretation of a river bank as a natural harbour requires an analysis of the archaeological record in the terrestrial zone and the hinterland of the potential harbour site. Not only excavations, but also a big range of archaeological prospection based on field walking, LiDAR scans, aerial images, historical maps, geophysical measurements and drillings could offer significant contributions for the identification of a riverine harbour without specific constructive elements.