The definition and concept of Spatial Integration in historic cities or towns is not accurately defined as it has been seen as an essential component of the present integration in the cities of towns.
According  to European Spatial Development Programme (ESDP) under the Noordwijk project, "Spatial integration expresses the opportunities for and level of (economic, cultural) interaction within and between areas and may reflect the willingness to co-operate. It also indicates, for example, levels of connectivity between transport systems of different geographical scales. Spatial integration is positively influenced by the presence of efficient administrative bodies, physical and functional complementarity between areas and the absence of cultural and political controversies."
In itself, the term "interaction" can seem at least as global as the one of "integration". However, this term, often coupled with the "spatial" or "territorial" qualifier is often used in scientific literature, in particular by geographers. In a wide sense, the concept of spatial interaction can be related to any kind of relationship between places (connexity, similarity, flows, and proximity) and one could assimilate the analysis of spatial interaction to spatial analysis in itself, or even to geography.
In the practice of (mainly geographical) research, spatial interaction often takes a more limited and technical meaning and may refer to a phenomenon described as "decreasing of the intensity of flows with distance". Different spatial interaction models have been built in order to give account of this phenomenon, many of them relying on the general gravity model, based on distance and on relative weights of the considered entities. Taking into account the ESDP definition, its global approach as well as the history of the criterion, it seems that "interaction" must be understood here as a rather comprehensive concept, that cannot be directly limited to some domains of relationships, nor even to spatial interaction as it is generally understood. For example the definition mentions "interaction between areas" rather than "spatial interaction", which could indicate that distance is not necessarily seen as central (maybe because the concept of distance is more specific of another criterion, "Geographic position")
The ESDP definition, through its reference to "willingness to co-operate" and to "absence of cultural and political controversies", also indicates that the social and human aspects play an important role in an open minded approach of the concept of spatial interaction. Besides its various interpretations, use of the term "interaction" in the definition of the Noordwijk draft of ESDP can also be seen as conveying some implicit ideas through its etymology.
Spatial integration and (spatial) cohesion:-
There is often reference to the terms which are or their meaning is related or closed to the integration in the European documents. In the Article B under title I of Treaty of European Union, the most often term under the aims and objectives, is the economic and social cohesion. There is no specific definition of cohesion (Economic and social) in the Treaty, but there is reference is to reduce the disparities between the levels of development of the various regions and the backwardness of the least favoured regions, including rural areas.
The analysis of the first report on social and economic cohesion describes the situation of the European regions in the same perspective of assessment of inequalities and of their trends. In those terms, cohesion seems closely related to the idea of homogeneity and Spatial (or territorial) cohesion is relatively less mentioned compared to social and economic cohesion.
Spatial integration and co-operation:-
The Noordwijk project of ESDP introduces in its definition the concept of "willingness to co-operate", as a basis for spatial integration. This adds an important dynamic element to understanding of territorial (or spatial) integration. Co-operation is often associated to integration, although there are some fundamental differences between the two concepts.
A priori, the concept of spatial interaction, which is at the core of the definition of spatial integration, has no positive or negative sense. Spatial interaction generally relies on human motivation (even if natural phenomena such as floods may cause spatial interaction), but these motivations might not be shared by all actors nor lead to win-win situations.
In contrast, absence of co-operation may result either in a limited level of spatial interaction, as relationships will not be supported by all actors, or in unbalanced relationships solely ruled by the law of the strongest. Lack of co-operation can be observed in practice in some cases where actual relations are less than one would expect in view of shared interests, physical possibilities available, or presence of spatial systems to manage (e.g. river basins). But absence of co-operation may also exist where integration (in terms of interactions) is strong, and in those cases it may have harmful effects for some of the partners.
Although the ESDP mentions the "willingness to co-operate", it must be said that co operation does not always rely on willingness but also on need to co-operate. This allows us to distinguish between situations that require co-operation (even if the partners are somewhat reluctant) and situations where spatial integration is actually weak but the "willingness to co-operate" exists. In the second case, certain material organisational changes may lead to an increase in the significance of relations between areas.
Attempting to translate the concept of "spatial co-operation" into indicators is recognised as being a very difficult task, as co-operation mainly relies on a "state of mind" and on organisational patterns that do not necessarily imply easily measurable phenomena.
Networks of places:-
For many authors, it is useful to reflect further on how places are linked, in order that integration might occur. Places are no longer considered as simple geographical constructs; rather they are defined through social analysis (for a review, see Amin and Graham, 1998). These stress that places are "articulated moments in networks of social relations and understandings" rather than "areas with boundaries around" (Massey, 1993; 66). In this configuration socially-constructed places are "noncontiguous, diverse, dynamic and superimposed. As well as being bound to place-based relations, cultural, social, economic, political and environmental links and relations can be stretched across space" (Graham and Healey, 1999 (forthcoming)).
This partially reflects a more sophisticated analysis of how networks of cities and towns interact, an area that Theme 2 explores further. As Dematteis notes we have witnessed the "passage from a functional organisation in which the centres are graded with a multi-level hierarchy (as in the models of Christaller and Lösch) to interconnected networks organised on the basis of the corresponding complementarities of the nodes and the synergies produced" (Dematteis, 1994). It also reflects an understanding that it is not places which interact but the people and organisations (actors) which inhabit that space.
Geoff Mulgan (1997) labels the current era one of 'Connexity'. This reflects the ESDP's definition of spatial integration as: "Opportunities for and level of interaction within and between areas". In Mulgan's view cultures, economies, social worlds, politics and environments all become driven by logics of increasingly intense interconnections and flows, over larger and larger geographical scales. A growing range of economic, social, and cultural interactions which are "both in place and out of place" (Adams, 1996; 279) are being supported by modern communications technologies (Graham and Healey, ibid.). Of course, it is possible that connections may only occur between specific sections of society. We may therefore witness different social geographies of spatial integration.
The Noordwijk project of ESDP suggests that measures of spatial integration will include levels of linkage between transport systems at different geographical scales. However, a fuller interpretation of the conception offered above implies that spatial integration is wider than simply transport linkages but includes all transactions (or flows) between areas.
To Mulgan, the growing importance of network-based connections means that economies are increasingly driven by "the logical or 'virtual' regularities of electronic communication, a new geography of nodes and hubs, processing and control centres. The nineteenth century's physical infrastructures of railways, canals and roads are now overshadowed by the networks of computers, cables and radio links that govern where things go, how they are paid for, and who has access to what. The physical manifestation of power, walls, boundaries, highways and cities, are overlaid with a 'virtual' world of information hubs, databases and networks" (Mulgan, 1991; 3).
India: - According  to Jordar, Souro D., "Spatial integration is the combination of all the activities like economic, social and physical which can be achieved by the modern spatial planning tools and techniques, different and dual modes for the participation towards development in the cities."
There are very few cities in India which have undergone planned development by using the modern spatial planning tools and techniques towards spatial integration. The author signifies the role of resources like land and infrastructure in the spatial integration of cities. Moreover, the role of modes like public and private sectors, public/private sector for the development of spatial integration, is also most important for spatial development.
Brazil: - According  to Edja Bezerra Faria and Valerio Augusto in their paper, "Spatial Integration/Configuration is a set of independent relations in which each is determined by its relation to others and the fundamental correlate is of the spatial integration/configuration is movement ".
But according  to Hillier, (1996, 35/152), "The structure of the grid considered purely as a spatial integration/configuration, is itself the most powerful determinant of urban movement, both pedestrian and vehicular. Because this relation is fundamental and lawful, it has already been a powerful force in shaping our historically evolved cities, by its effect on land use patterns, building densities and part-whole structure of the city".
South America: - According  to Poul Ove Pedersen and Walter Stöhr "Spatial development and Economic Integration is associated with spatial distribution of physical & geographical patterns, transport networks, economic activities, natural resources & different policies etc" and change is these factors can change the spatial integration pattern in the areas/city or in the region.
South Africa: - Within the constitution, for the basis of new development and local government system, white paper was introduced which highlights and committed to cover all the sectors to meet the demands of the society. According  to it, "Spatial integration is a strategy for doing away with the expensive and exclusionary land-use patterns of apartheid. It seeks to enhance the efficiency of the city by placing residential development closer to job opportunities, and reduce the costs of development by exploiting surplus bulk infrastructural capacity. Spatial integration also has a social dimension and can increase the access of low-income residents to facilities and opportunities in the city". For the Integration of cities, towns and rural areas which has different spatial dimensions like social, an economic etc, the objective is to create more efficient and equitable cities, towns and rural areas.
In Contrast to many literatures, Hillier's establishment of a theory of space as configuration and series of related methodologies, called space syntax, (Hillier & Hanson, 1984; Hillier, 1996) that spreads a new light on the spatial formation of area structure. Hillier (1987, 1989) first suggested that optimizing correlations between spatial configuration measured by spatial integration and movement rates and the growth of settlements changes the pattern of Integration.
The concept of spatial integration was also identified in the European Spatial Development Programme (ESDP) throughout the various versions. The First document which was on spatial planning issues, when it appeared first time in 1994 and it was centred on the specific aspect of cross-border relationships but slowly it came out with wider vision which was summarised later in the first official project of ESDP. After the evolution of Noordwijk, 1997, the next version of ESDP was produced in Glasgow in 1998 which came out with removal of few terms (economic, cultural) while it maintained the definition. Later on, the final and official version was adopted in Postdam, 1999 in which no indications on the definition of spatial integration or the concept of spatial integration. The CEMAT also gave same kind of Guidelines for Sustainable Spatial Planning to maintain spatial balance.
It was also asked to produce synthetic indexes which should be able to take into account the seven dimensions of spatial differentiation in a global approach. These criteria, it is argued, provide a starting point for recognising and assessing the spatial dimension of the ESDP and, in combination, have a particular value for the purpose of spatial analysis.
As it was recognised, spatial integration is, perhaps, one of the criteria which is most directly related to the concept of spatial planning itself. Consequently, and by virtue of its comprehensive nature, it may often overlap the fields of interest of the other criteria. From the start criterion has an overlay with the criteria "Geographical position" (1.1) but also with all the other criteria of spatial differentiation and probably with all the other parts of the call for proposals. In other words, the question of spatial integration is present everywhere in the SPESP and it is well known that "what is everywhere is also nowhere".
For example, there is a potential overlap between spatial integration and geographical position on the questions of distances and of transport and communication infrastructures. Some less obvious overlaps may occur with social integration (about integration factors such as language, culture, political sensitivity), with economic strength (economic functions generating relationships), with land use pressure (impact on migration moves through effects on land prices) or with natural and cultural assets (common resources that can account for spatial relationships). Links exist also with work on the urban - rural relationships typology and urban - rural partnerships considered under theme 2.
All this indicates that one of the first tasks related to the work on this study strand is a deepening of the concepts, taking into account not only the concept of spatial integration itself, but also some other related concepts that may help to delineate the field of the study.
The previous points all go to show how interrelated the concept of spatial integration is with concepts such as economic and social integration. Far from serving to narrow its field of application, the body of literature concerned with spatial integration is in fact serving to widen its influence.
This raises the question of identifying the specific nature of spatial integration, and reminds of another similar question, that is identification of the specific nature of spatial planning / spatial development. In both cases, the multi-facetted nature generates a difficulty to focus on specific issues, notably because isolating the spatial dimension of a reality is a rather abstract exercise whose practical purpose is not always obvious to perceive.