Urban Morphology: The Significance of Urban Space History

Abstract

The importance of urban morphology lies with its interdisciplinary approach from architecture over history to geography. However, often enough, its scientific methods only marginally start from the urban space itself that makes morphology tangible in the first place. With the ongoing specialization of the sciences, strong isolations occur, be it related to the singular development in one place or the dissection of a temporal period, a functional context, or a numerical method. And yet, there are abundant general methods already investigated and tested to deal with the historic development of urban space. The aim of an Urban Space History is thus to explain the importance of the consideration of urban space; to recall the existing methods; and, thus, in a further development, to develop a low-threshold scientific approach that is helpful, or even indispensable, in retrospective and prospective work with urban space. This paper summarizes the spatial–historical perspective, as it has been developed since 2006 at the universities in Aachen and Buxtehude and is today a significant part of the teaching at both institutions.

1. Introduction

Our contemporary production of urban space increasingly lacks a comprehensive approach to the past—at times, even a profound examination of the present. The industrialized planning and building processes—from their very beginning in the 19th century onwards over their acceleration by the development of modernization principles in the 1920s, their implementation after World War 2, and ultimately their spread all over the globe after the 1990s—started from a spatial understanding that took a given locale as an empty canvass on which to create a whole new picture. This inadequate approach reveals itself in today’s project management, which regards existing buildings and social neighborhoods, archaeological findings and monument protection, and building ground issues, as well as the discovery of aerial bombs or landmines, unanimously as threats to the success of the projects and, eventually, as reasons for subsequent claims and an unexpected rise in building costs. Projects are developed backwards from the proposed image of the result, rather than from the locale that is to be developed. Alas, usually these projects do not only neglect the history of urban space; usually, they also destroy its constituents in due course of the project’s realization.

Unfortunately, even the scientific disciplines that deal with urban space are increasingly falling prey to such a misconception. A major problem here is that the relevant knowledge and understanding has been steadily declining since the 1920s. Fair enough, many new significant findings and methods apparently render older ones outdated; however, this is not true for the significance of a general approach towards the locale. When Bauhaus director Walter Gropius (1883–1969) proclaimed the necessity for his students to free themselves from the past and to withdraw from the books, he was still relying on a profound historical understanding of the past architecture by his students—not the last for them to know, from what to free themselves. When the modern understanding of planning and building that included a wide range of philanthropic and socio-economically efficient solutions to prevailing issues happened to accelerate, also the sciences moved away from the comprehensive significance of the history of urban space. What is common today is focusing on a singular development in one place or the dissection of a temporal period or a functional context, as well as the development of detached numerical methods that promise an alleged objectivity [1].

Still, dealing with urban space and its constituents, we have a very simple starting point: it is the urban space itself that will reveal plentiful information. With little effort, it reflects comprehensively how elaborate the necessary approach must be, depending on the task at hand: the examination of the past or the development of the future. Thus, urban space history, as it is proposed as an intrinsic part of urban morphology, as well as a tool for the planning and building sciences, is a highly significant and universal task that should be tackled in every project involving urban space—regardless of the respective cultural or academic background1.

2. Layers and Stratification

Urban spaces are the result of historical processes, which manifest themselves in the rising buildings and their construction history, as well as in archaeological remains. Together, they form the most direct and generally most accessible source for the history of a city’s origins and development, even before any pictorial or written record [2].

Interestingly enough, it is very often the crucial information hidden underground that is not taken into account for a thorough understanding of a given locale (and, unfortunately, many constructions lead to a careless destruction of history and a severe harmful impact on the traditional urban space). Thus, first of all, the more or less pronounced settlement horizons at a location must be taken into account. These, in their stratification, determine the most recent cultural layer of today. It is essential for the consideration of this stratification that the horizons that appear planar today originally had a spatial dimension. This was—if you like—subsequently compressed and stripped of its spatiality. Despite the vivid simplification, the reality of excavation science is challenging: the features belonging to a stratum can be located at different absolute heights or at different distances from the current horizon and thus provide initial indications of the historical relief of the city.

The spatial dimension within each cultural layer is represented by a complex structural fabric. Its complexity is based on a large number of factors, ranging from the demands and resources of the client to the skills of the planners and builders and the behavior of the users. These factors have concrete effects that can be seen in the building or in the remains of the building. However, conversions, extensions, and new buildings not only shape the building itself but also its surroundings and thus its relationship to the neighboring buildings. Historical building research identifies these processes on the basis of the rising building structure and thus determines the building history of the structures.

What both archaeological and building research approaches have in common is that their findings—even if they are subject to interpretation—always represent empirical evidence: without assignment to a stratum, without evidence within the building structure, hypotheses must remain doubtful, even if they appear plausible or are even described in other historical sources. Conversely, it must be conceded that a building was self-explanatory at the time of its existence: a larger or more elaborate building in comparison to other buildings of the time will also have to be considered more impressive, even if other sources make no statement in this regard.

As a continuous composite, urban space summarizes the past compressed spatiality and the present rising buildings. However, it would be too short-sighted to view urban space only either archaeologically or in terms of architectural history. A decomposition into the components of topography and boundary buildings, as well as their individual disciplinary examination, would also appear to be of little use. The spatiality of the most recent cultural layer must always be placed in relation to the former layers. Corresponding deficits can sometimes be observed in the history of urban development, which often only deals with the architectural history of the city [3,4,5,6,7], or in the mostly geographically motivated urban morphology [8,9,10,11,12].

Urban space is more than the sum of its structural components. A majority of the mutually influencing physical features above and below ground that are represented in the space are of particular importance for a consideration of the history of urban space—beyond the numerous other ephemeral indications that are nevertheless inscribed as traces in the physical features.

Giambattista Nolli (1701–1756) contributed with “La Nuova Topografia di Roma” (“The New Topography of Rome”), one of the best-known examples of a comprehensive mapping of urban space and thus a seminal example for the methodical approach of urban space history [13]. It was published in 1748, after 12 years of surveying and engraving, containing a detailed depiction of the city center of Rome (intra muros) on 12 plates, 80 by 54 cm each. The novelty of the mapping lies in the fact that not only are the streets and squares shown, but also places that can be regarded as enclosed public spaces, such as courtyards, churches, monasteries, public buildings, etc. In addition, Nolli has also included ancient Roman remains, such as stadiums, circuses, baths, aqueducts, etc., and thus emphasized their importance for later urban development (Figure 1). Overlaid with current satellite imagery, the sustainability of the oldest strata of Rome in today’s urban space become impressively clear.

3. Locus and Topology

The starting point for an investigation into the history of urban space is always a real place or locus (i.e., locale), where the historical stratification and the structural fabric can be experienced in their physical majority [14]. The context of the archaeological and structural fabric of a place establishes the phenomenal autonomy, as well as the uniqueness, of the respective urban space.

Within the discussion of architectural theory, the importance of people for the genesis of places is undisputed: a place only manifests itself through structural activity [15]. Building on this, it is justifiably accorded with a quality that goes beyond objectifiable data and is justified by its complexity [16]. However, recurring subjective perceptions and collective views quickly come to the fore, focusing on people’s particular relationships to places. In this approach, places are then seen as constructs of an immaterial nature; such an “animated place” (genius loci) is then primarily based on the perceptions, memories, and interpretations through the different ages.

This tradition of thought can be traced back to antiquity in Europe, but then played a major role in Romanticism, in the fin-de-siècle, and again since postmodernism. Personal or communal memories and feelings, individual projections, and traditional and self-confirming images lead to a “phenomenology of the genius loci” [16,17]. This independent approach to places uses elementary, atmospheric, and material categories and often creates cosmological, mythical, and mystical contexts that occasionally exhibit hermetic traits. They then become part of an academic narrative or the subject of a teleological view.

However, such concepts are a hindrance to an investigation into the urban space history if the analysis of the actual findings is disproportionate to the cultural–scientific interpretation and the necessary empirical evidence is neglected. The described majority of mutually influencing physical findings must be a constant point of reference and, above all, a corrective to any evaluation, even if any imprecision can never be completely ruled out: “atmosphere”, “mood”, “poetry”, etc., should not override a view of urban space history. There is often only a fine line between a technical quantitative reduction and a psychologizing qualitative exaggeration.

What is essential, however, is the extent to which the individual findings reveal a design intention: Were typical decisions made that can be assigned to a specific period of origin or a definable formal intention and make a clear design goal recognizable? Which cultural or chronological contexts have become effective for the design and thus also act as a creative origin? Consequently, a particular urban history of the location can be derived from the observation of special factors within a stratification or composition, which in turn is part of a supra-local general urban history. This is precisely where the phenomenal aspect of a place lies in urban space history.

The historicity of the urban space is therefore not only founded in its actual historical layering and arrangement but also in the integration of the respective findings into a cumulative horizon of recurring, as well as outstanding urban space formations. Taken together, these form a constantly growing historical topology of space.

Camillo Sitte (1843–1903) is considered one of the inventors of “Städtebau” (literally: the building of cities). He was the first to coin the comprehensive German term, which not only focused on the new construction of urban extensions in the 19th century but also had the entirety of the built cities in mind. With his pivotal book Städtebau nach seinen künstlerischen Grundsätzen (The Building of Cities According to Artistic Principles) originally from 18892 [18], in which he presented a wide range of analyses of existing cities in Austria, Germany, Italy, and France, he must also be regarded as one of the first historians of urbanistic development. His focus was always on the space from which he derived his findings and which he always inspected personally. In the example of the Via degli Strozzi in Florence shown here, he illustrates the importance of the different spatial effects of the Palazzo Strozzi—in stark contrast to the fashion of the time to expose important monuments by demolishing the adjacent buildings and thus destroying the traditional urban fabric (Figure 2).

4. Historicity and Morphogenesis

Historicity is an essential principle of the phenomenal autonomy of urban spaces that goes beyond the historicity of the individual physical components. Consequently, a historical examination of urban space must be more than a composite of scientific approaches that only focus on its partial aspects.

This does not mean that urban space history does not make use of individual methods of archaeological and architectural building research. In principle, the same scientific principles and approaches apply: the autonomy and essential uniqueness of the object of investigation necessitate an inductive methodology that begins with an investigation of the physical space. As in building research, rules and exceptions to the design must be identified and their backgrounds understood. It is often possible to draw conclusions from logical connections and building processes without in-depth knowledge of the location and that are then supplemented by a comparison with local and regional developments.

In principle, physical perception must be regarded as a prerequisite for any analysis of urban space history [19]. This includes a conscious description of the place to be examined, starting with the orientation of the observer. Then, the division of space and, if necessary, geometric figures must be determined, supplemented by an analysis of the integration into the surrounding urban structure and any changes in the terrain. The structural questions posed to the site quickly point to past settlement horizons, which can explain deviating forms or geometries in today’s urban space. This can already be achieved through a sketchy extrapolating reconstruction of the deviation in situ—without consulting historical maps.

The ground areas and terrain are followed by the spatial boundaries and structural features of the site. Reliable results are achieved through quantitative and qualitative comparisons and statements on the homogeneity and heterogeneity of the buildings and building sites in terms of size, form, and materiality. Basic knowledge of historical building research and history is obviously helpful in these considerations. Greater certainty in the chronological or epochal classification of buildings shortens an investigation enormously, but it is not indispensable. As a rule, a careful consideration of the limiting buildings will already allow a relative chronology to be established that is sufficiently plausible.

In any case, the peculiarities that can be observed are revealing, especially the joints, breaks, and deviations in all spatial boundaries—be it the surrounding façades or the terrain. They can be used to derive insight into the building period (the more expensive patrician house compared to the simple craftsman’s house), as well as successive processes (the residential buildings built into a Roman theater or the modern city palace built on the site of several medieval residential buildings). The same applies to urban morphology and structure: changes in orientation and development, alternating forms of arrangement, or changes in density and grain.

The study of urban space history deals with the morphogenesis of urban space based on the status quo. Its methodology is strictly inductive and works essentially by identifying rules and deviations. The examination of different situations of an urban space ultimately enables the “reading” of development rhythms [20].

Wolfgang Rauda (1907–1971) published, in 1957, “Lebendige städtebauliche Raumbildung” (“Lively formation of urban space”) as a study of the asymmetries and rhythm of German cities, and it has unfortunately received little attention to date [21]. However, his work provides us with a useful tool for investigating urban space, regardless of its regional focus. By juxtaposing site plans with the according elevations of street and square walls, irregularities can be easily identified and assist in identifying places where further investigation is required to explore the historical layering of ownership and path relationships (Figure 3). At the same time, this contributes to a first spatial understanding of a given locale on the basis of built facts—and thus lies beyond atmospheric or emotional biases.

5. Context and Palimpsest

As places of action, urban spaces are also the subject of present and future design processes. An analysis of urban space history is therefore never an end in itself. Rather, it is an indispensable part of the apparatus of the preliminary urban planning investigation and survey of a building site or a planned area for a project, so that the new building task can be adequately contextualized.

In this context, the past fifty years have gradually led to a paradigm shift in design intentions. Whereas the interwar and postwar periods were characterized by strict functionalism and internationalism, in which the spatial context played a subordinate role, since the end of the 1960s, the reference to place has once again become more prominent in architectural theory [22]. This is reflected in the corresponding buzzwords and guiding principles, starting with postmodernism [23,24,25], regionalism [26,27,28,29], and building in existing contexts and contextual or identity-creating building. Since then, the failure of the modern project has been invoked in various ways, and more traditional urban spaces have been propagated.

In many places, the preservation of the cityscape first ensured an often urgently needed infrastructural modernization of the neglected old towns [30,31,32,33,34]; then, new quarters were created in rows in traditional forms3 [35,36]; and, finally, many cities underwent reconstruction measures of individual building ensembles up to the reconstruction of entire districts4 [37,38,39,40,41]. Irrespective of the sometimes-respectable spatial design effects, this new spatiality extends above all to the architectural backdrop. Construction and production continue to be subject to modern construction industry processes, which confront building projects with an industrial totality that generally overrides the complex context of a locale [42].

Consequently, today’s reference to a locale is primarily about a naïve image of the city: traditional parcel layouts, storeys and heights, archaeological remains, socio-cultural dominants, etc., remain unconsidered or are even destroyed by the construction measures. As a result, today’s urban planning and building construction are also getting rid of the historicity of places. Their projects—like the projects of the first and second modernism—regularly lack an urban spatial significance that places the building activity in an ongoing context. Insights into urban space history can thus contribute to sustainability and the conservation of resources, as can the respectful further development of existing buildings and the intelligent reuse of existing structures.

Like many other arguments of the current social readjustment, such considerations are not fundamentally new; however, the “inhospitality” of our cities has only become part of the specialist discourse in relation to the failure of modern large-scale housing development [43]. The debate about the lack of history in design has also only encouraged a move away from functionalist construction, which is also stylistically recognizable as functionalism [44]. Exhortations against the consumption of space, suburbanization, gentrification, and the waste of materials, on the other hand, were ignored and ignored. Instead, new spaces were synthetically created that wanted to work on their own—without regard for the existing local context.

The history that is reflected in urban space testifies to the responsibility of those involved not only towards the present but also towards the future—in which today’s present will have passed. As with a palimpsest, which is written over and over again, such responsibility does not require the blind preservation of the status quo, but rather the constructive shaping of the future.

Gordon Cullen (1914–1994) approached urban space through his “Townscape” considerations, which he published in 1961 [45]. While initially starting from the already described troublesome atmospheric point of view, which ought to include also the ephemeral components of space (from the ever-changing advertising panel towards human interaction), he nevertheless proposes simple methods of analysis that plausibly describe the factual and persistent space. Unfortunately, also his book, which was deliberately meant to be a guide for understanding the complexity of urban form for students and scholars alike, lost its range over time. Despite a “concise” reprint in 1971, today we find less and less implementation of his approach—in urban design, to which end he has written his study, as well as in the field of urban morphology (Figure 4).

6. Perception and Prospection

The perception of urban spaces itself is also a process that has an inherent historicity and responsibility under professional conditions. From the perspective of architectural science, an investigation of urban space therefore resembles retrospective or decompositional design work, which—like design itself—gains through routine.

To this end, it is also helpful to develop a personal historical topology of spaces—a process that obviously takes time and practice. Academic teaching that pursues urban space history often encounters a great lack of understanding of historicity per se. In a synchronous world in which every piece of information can be called up at any time, it is increasingly difficult to comprehend diachronic processes and to link different moments with one another logically. Under the (also modern) impression of a supposed simultaneity of things, general statistical and numerical methods and remote sensing appear more efficient than a methodical examination of concrete and specific situations on site, as can be observed in the contrary positions by Winy Maas and Sanford Kwinter, the former pinpointing the density of a city, and the latter pinpointing the biopsy at a given locale [46].

The second obstacle appears to be the scale at which urban spatial studies have to be carried out—comparatively large areas often have to be examined with less precision. Where a structural analysis rarely manages without a personal inspection, it is often avoided in urban planning. In order to approach the unfamiliar scale, a detour can therefore be taken via a mass model, which makes the object of investigation commensurable. In it, the rules and deviations of the topography and the buildings can be experienced by hand. The model thus forms a first approximation to a physical perception of the urban space, albeit still without the irreplaceable stay in situ.

The necessary preliminary work for the mass model also provides further significant clues. In relation to the urban structure, these are the development networks, the building uses, the densities, and the granularities; and, in relation to the urban form, the different building developments, the forms of arrangement, and the building heights and storeys. The structure is recorded on a parcel-by-parcel basis in building use plans, and the morphology is recorded on a mass scale in figure-ground or Nolli plans. An initial investigation of the urban space is then carried out using the red–blue plan, as proposed by Uwe Schröder (*1964), which not only maps the quality of the various spaces according to their enclosure and spatial commitment but must also determine those active and passive elements that determine these different qualities [47]. This approach, developed in the last decade, happens to be the most recent analytical approach to the historic urban space, representing another significant tool for urban space history, which evaluates the current spatial situation and explains spatial contexts.

The knowledge gained through the analytical steps of mass model, use plans, figure-ground, and red–blue plan provides a robust basis for the on-site investigations into urban space history, in which the assumptions made can be checked and classified in relation to the gaps, breaks, and deviations, and situations that have not yet been discovered can be integrated. The most successful method for this is Cullen’s “serial vision”, which can be easily executed for, as well as adapted to, the respective research task. The contextual structure of the urban space with its continuities and discontinuities in the space-defining surfaces and bodies quickly becomes apparent in the graphic recording of different successive situations and confirms the evidence necessary for the investigation.

Urban space history thus provides no methodological novelties. As with spatial design, its theoretical foundations also lie in the architectural discourse of the 19th century. However, it has the essential task of repeatedly demonstrating the significance of urban space for truly contextual sustainable building and anchoring this in today’s discourses.

7. Illustrative Studies: Arras and Hamburg–Harburg

As part of the teaching of urbanism and design at Buxtehude University of Applied Sciences in Germany, the method of urban space history is used to examine the traditional urban space, as well as to identify the need for action in urban development.

In the winter term of 2022/23, one student group examined the development of Arras in France, a place none of the members had ever visited before, and it was therefore chosen. In addition to the technical experience of the 1 to 1000 scale for the topography and the urban fabric, the students examined especially the spatial relationships between the various monumental edifices and the city’s secular residential and commercial buildings. They gained important insights by differentiating between area-related usage attributions and physical characteristics of the buildings. The overall view of the analysis levels impressively shows the allocation of the monumental edifices to the respective open spaces (Figure 5). It became clear that, in Arras, the relationship between narrowness and expanse, already described by Sitte, was very often used to emphasize the special buildings from the mass of buildings and that this concept persisted throughout history. However, the next step, the personal site inspection, could unfortunately not be carried out during the study period, so the investigation into any irregularities of the urban space could not be carried out—this also means that a stratigraphic disclosure is pending to complete a comprehensive analysis according to urban space history.

In the summer term of 2023, however, another group of students examined the Schwarzenbergpark district in Hamburg–Harburg as part of a prospective analysis. Starting with the above-summarized investigation’s four-step routine, the investigation was largely extended by personal inspection and documentation. For this purpose, completely regular and incompletely regular fabrics were distinguished from irregular developments, and, in particular, the transition points and the spatially unframed areas were identified with the help of “serial vision”. The students experimented with freehand sketches in the spirit of Cullen, as well as with contemporary representations, overlaying aerial photography with digital mass models (Figure 6). The results showed a number of locations that were proposed to be improved through various spatial measures (in structures and landscaping, functional and formal), without counteracting or even disrupting the traditional morphology of the location. By applying the urban space design method, it was not a more or less creative idea or emotion about the locale that became the starting point for a design proposal, but the location formed the basis for a genuine spatial development of the urban quarter and, hence, a true continuation of the different historic layers at the locale.