Imagine a student reading Odysseus’ Cretan tale at Odyssey 19.172–84. When faced by a string of unfamiliar names – in addition to ‘native Cretans’, there are Achaeans, Cydonians and Dorians, as well as the individuals Minos, Deucalion, Idomeneus and the speaker, Aethon (Odysseus in disguise) –, they use their digital edition to find out more about each of these people and their places of origin. A personal name opens an online encyclopaedia entry, while clicking on a place launches an emerging world beyond the single text – an online atlas that provides information about the place's toponymy, form and exact location as well as links to other resources (textual and archaeological, ancient and modern) about this place, including those to which our student has contributed. The year? 2023 (Figure 1).Footnote 1
This scenario summarises an example of current work that uses digital technology to explore notions of space and place in Classical Studies, the most significant achievements of which this review essay attempts to survey.Footnote 2 Our aim is to provide a snapshot of the latest digital-based research into ancient spatiality – both places on the ground and those represented in texts – and highlight the ways in which Classical Studies have also contributed to technological innovation. Our remit is particularly wide not only due to the fact that work in ‘Spatial Classics’ is inherently transdisciplinary, extending far beyond a narrow Graeco-Roman focus, but also because Spatial Humanities itself is a new and emerging multidiscipline.
The methods and applications represented by the description ‘a spatial analysis through digital technology’ are wide-ranging and diverse. Our review will discuss tools, such as GIS and other mapping software, and practices of annotation and geo-resolution, as well as the emerging technology of Linked Open Data. Throughout we highlight scholarship, projects and initiatives that best illustrate how an ever-expanding set of geospatial tools and methods are offering new ways of viewing and experiencing ancient places.
THE SPATIAL HUMANITIES
The spatial turn has recently been reinvigorated by technologies with new modalities for visualising and manipulating information, at the same time contributing a renewed emphasis on the impact of spatial perception and social construction of space.Footnote 3 This phenomenon has given rise to the multi-disciplinary field of Spatial Humanities.Footnote 4 At its core is the idea that technology and particularly digital mapping can support ‘locating historical and cultural exegesis more explicitly in space and time’.Footnote 5
Arguably the most influential technological innovation on historical or archaeological research has been GIS (Geographic Information Systems) – a system that facilitates the gathering, management and analysis of data through its plotting in space. By enabling the visualisation and manipulation of data according to location, GIS has contributed fresh perspectives on several important topics, from health policy to conflict,Footnote 6 as well as establishing new ways of reading literature and history.Footnote 7 However, because it provides a highly precise way of organising information based on point geometry, GIS is less well equipped to address issues of uncertainty, ambiguity and plurality that typically characterise literature.Footnote 8 In particular, its use for the study of the past is problematic, since the nature of GIS determines that data is plugged into and viewed via a Cartesian coordinate structure, while pre-modern views of space appear to privilege non-Cartesian modalities of spatial representationFootnote 9 and possess different foundational criteria for defining ‘place’ and scientific authority.Footnote 10 Along these lines, the humanities raise fundamental epistemological and ontological concerns for spatial technologiesFootnote 11 and provide an important challenge for the development of a more diverse array of technologies.
While embracing Spatial Humanities methods and tools, Classical Studies is simultaneously providing a critical lens through which new ways of thinking about ‘place’ are emerging. One reason for its pioneering role is its transdisciplinary nature.
ARCHAEOLOGY AND MATERIAL CULTURE
Being rooted in the examination of landscape and human interaction with it, archaeology was an early adopter of GIS technologies and has been at the forefront of their development. Over the past century archaeological practice has evolved increasingly sophisticated quantitative methodologies for the study of a place and its physical traces,Footnote 12 where ancient cultures, their activities and settlements are conceived of leaving behind a range of ‘signature landscapes’ that can be modelled. Alongside these scientific trends, and especially since the 1980s post-processual critique, approaches drawing on phenomenology have emerged, which emphasise historical context and subjective interpretation.Footnote 13 This in turn has led to a growing methodological divide between digital-based and more discursive methods of spatial analysis.Footnote 14
Landscape-oriented approaches have increasingly employed GIS methods and tools for the historical analysis of archaeological sites, ancient trackways (so-called ‘hollow ways’), palaeo-canals and other human-related or human-made features.Footnote 15 Inevitably, over-reliance on exact quantitative analysis leads to abstraction of these signatures and requires a developed qualitative framework into which narratives and models can be incorporated.Footnote 16 The quality and variety of datasets are also an important factor. For example, line-of-sight (LOS) calculations across a landscape should also take into account topographical changes over time, vegetation index, the scale of different objects and agents, and seasonal environmental factors.Footnote 17 Many of these elements cannot easily be measured without taking into account complex embodied experiences of the same landscape across time and through the eyes of different agents.
Much of the recent advancement in spatial archaeology has depended on acquiring increasingly sophisticated remote sensing data.Footnote 18 Examples include: historic aerial and spaceborne imagery; multispectral and hyperspectral imagery; synthetic aperture radar or SAR; and LiDAR (Light Detection and Ranging). All these approaches enable the study of land features beyond what can be seen by the naked eye. After the acquisition of spatial data on different scales (from landscape and site to the micro-level of objects and samples), various digital methods can be deployed to analyse and model their historical and social complexity.Footnote 19 Many of the breakthroughs in landscape analysis since the 1990s have been due to the creation of digital elevation models and digitised structured data of previous archaeological surveys by LiDAR and SAR technologies. Drone and satellite imagery have also been critical, especially declassified Cold War-era images like those used to construct the Corona Atlas and Referencing System project or U2 aerial photography.Footnote 20 Satellite and aerial imagery provide a picture of the region of the Near East prior to its industrialisation and dam construction, which is helping to facilitate more accurate remote and ground surveys (Figure 2).Footnote 21
One topic that has benefited significantly from these new forms of remote sensing and their computational analysis, termed by some the ‘geospatial revolution’,Footnote 22 is the study of urbanism.Footnote 23 By enabling the discovery of the structure of different urban spaces and landscapes, these methods are prompting a re-evaluation of the field of early urbanism as established by Gordon Childe. Land use, palaeoclimate, ethnography, settlement patterns and morphology as well as the interaction of site remains with roads and especially water and hydraulic architecture are now being combined to provide a more extensive and nuanced understanding of the form of cities, levels of social inequality, and the interactions between cities and their hinterlands, including harbour areas.Footnote 25
Digitisation efforts are increasingly being facilitated on the spot through mobile-device software like Bruce Hartzler's iDig application, with the result that individual excavators can produce ‘born-digital’ data themselves. A related development has been Agent-Based Modelling (ABM). Using digital reconstructions of landscape and archaeological sites, researchers can place themselves in a virtual space and model their interaction with the environment (Figure 3). In this way, agent-based scenarios can draw attention to relevant parts of a landscape as well as to the possible kinds of interaction.Footnote 26 At the same time, ABM easily lends itself to the development of computer games and realistic 3D environmentsFootnote 27 as well as to archaeo-gaming strategies,Footnote 28 which can allow scholars to explore different remote sensing methods.Footnote 29 The potential of virtual reality (VR) and augmented reality (AR) platforms to model excavation and spatial data in 3D graphics for research and teaching is already being realised in projects such as Virtual Rome and Virtual Pompeii,Footnote 30 the 3D model of Babylon Footnote 31 and the growing field of virtual heritage at large.Footnote 32
There are, however, still many limitations to and problems with the application of digital technology in archaeological research and pedagogy. First, having an ethical approach to remote sensing is ever more urgent, especially when attempting to survey areas with at-risk heritage or endangered communities, as in the case of the EAMENA project in Africa and the Middle East.Footnote 33 Second, even in archaeology not all data models are best viewed within a GIS-framework.Footnote 34 Even if they are, critical scrutiny of digital applications needs to be facilitated, especially as the tools become ever more multilayered, complex and hard to understand,Footnote 35 such as connecting remote sensing data with groundtruthing data or the 3D imaging of sites (Figure 4).Footnote 36
Arguably, however, the greatest obstacle to combining narratives reconstructing ancient spaces and spatial data remains the ambiguity in both types of sources. Most attempts at visualising different interpretations of the same landscape at once use different notation methods, such as a variety of coloured dots or lines, half-lines etc. However, the denser a graphical expression, the more it loses its qualitative nature, to the extent that the connections to the sources behind the interpretation become lost, unclear or meaningless.Footnote 37 There is an urgent need to develop new digital ways to visualise interpretations in a manner that does not overburden observers with indigestible information. One step is to develop and establish conventions for modelling ambiguity in narratives and archaeological data.Footnote 38 Another solution lies in an increasingly popular form of digital application, namely network analysis. Work represented by Classical Studies in this field continues to break new ground, spawning large-scale projects (e.g. on migrations in the ancient Greek world) or textbooks,Footnote 39 as well as to disrupt old paradigms, not least in questioning the notion of single entities like ‘Greece’ and ‘Rome’.Footnote 40
Furthermore, there is a need to correlate remote sensing and ground survey data with other types of historical sources, including ancient texts. Noteworthy GIS mapping projects, which identify archaeological sites with textually known spatial entities of Mesopotamia, include the late third millennium bce BabyloniaFootnote 41 as well as Upper Mesopotamia during the second millennium bce.Footnote 42 One impressive manually aggregated site index, covering most of the ancient Near East, is Pedersén's 2007 Google Earth-based dataset, which includes a partial reconstruction of the Mesopotamian water system in the Neo-Babylonian period.Footnote 43 Another project, Geomapping Landscapes of Writing (GLoW), has collected all the sites at which cuneiform-bearing documents were found, including the quantities of cuneiform objects themselves (their gazetteer is deposited in Zenodo).Footnote 44 More recently, using the gazetteer and network analysis of the MAPA project, Clark, Altaweel and Gordin have connected archaeological data with long-term historical records from the southern Mesopotamian city of Uruk, to demonstrate that settlement size can be directly linked to changing state and government policies and local responses to it.Footnote 45 Even though this situation is rapidly changing, a serious deficiency remains in the digitisation and linking of ancient placenames from textual sources, modern printed gazetteers and maps.
FROM MAPS AND DATABASES TO TEXTS AND LINKED DATA
While the spatial turn in Classical Philology continues apaceFootnote 46 (see C. Schliephake's Profile on Ecocriticism, CR 72 [2022]), less well recognised are the interventions digital technology has made in more philologically-inclined research. Central to much of this activity has been the creation of place databases from texts and artefacts, which in turn has made it easier to map places encoded in narrative, to explore their discursive spatial configurations and to link to other resources.
The advent of digitisation technologies has revolutionised the management of geographical data about the ancient world. When in 1988 Talbert began work on what would become the Barrington Atlas of the Greek and Roman World,Footnote 47 use of GIS technology was limited to producing full-colour maps of the Graeco-Roman world, along with a map-by-map directory on CD-ROM. Even at that time, however, there was a realisation that digital technologies could facilitate the management of rich geographic information. This led to the foundation of the Ancient World Mapping Center, which maintains the data backbone of the Atlas as well as a collection of open mapping resources for the scholarly community.Footnote 48 In recent years the Tabula Imperii Byzantini – the first systematic atlas of the Byzantine world from the fourth to the fifteenth centuries ce – has similarly been negotiating the transition from print to digital,Footnote 49 enabling new insights into the dynamics of communication and power in the empire.Footnote 50
While cartographic representations from antiquity are invaluable due to their paucity, Graeco-Roman maps such as the Tabula Peutingeriana are critically limited by the printed book. Using the affordances of hypertext technology, the digital Tabula Peutingeriana includes a detailed database of features and names accompanied by high-resolution images, an extended commentary and geographic data from the Barrington Atlas, as well as an interactive viewer. Meanwhile, other initiatives have used GIS to map different aspects of ancient Roman space, such as the Stanford-based projects, the Digital Forma Urbis and Orbis (Figure 5). Orbis mixes traditional GIS methods with a probabilistic network model that allows users to simulate conditions of movement in the Roman Mediterranean of the second–third centuries ce and to explore, within the confines of a simulation model,Footnote 51 how lived experience was impacted by environmental and geographical factors. Orbis provided the basic conceptual and technical framework for the al-Ṯhurayyā Project, the first gazetteer of the Islamicate, which combines traditional atlas information with a network-based geospatial model, allowing the calculation of various pathfinding combinations.
Arguably the most decisive contribution to the field was the launch of Pleiades, an online gazetteer for places of the ancient world, formed out of the digitisation of the core place date of the Barrington Atlas. From its inception, Pleiades brought a critical cartography approach to the study of ancient geography by disentangling the notion of place from its location. In essence, Pleiades defined place not so much as a geographical entity with coordinates, but as a bundle of conceptual associations that exist independently of point geometry: an ‘un-GIS’ of cultural values, perception, toponymy, bibliography and relations (Figure 6).Footnote 52 Freed from the bonds of the printed book, Pleiades has continuously pushed the boundaries of the Barrington's Graeco-Roman world. This work has been made possible by the establishment of Pleiades as a ‘community-based’ enterprise, to which a wide range of scholars contribute data and editing. These two factors have helped enable the creation of similar initiatives in cognate disciplines, such as the Syriaca gazetteer, Norse World, the Mesopotamian Ancient Placenames Almanac (MAPA) and Kima.
In 1987, the year prior to Talbert's Barrington Atlas project, G. Crane founded the Perseus Digital Library. First published as two CD-ROMs before being launched online in 1995, Perseus has made thousands of classical texts openly accessible. At the same time, by adopting common standards for text markup, namely the use of TEI XML, Perseus has enabled the enrichment of texts through annotation, including morphological analysis and, crucially, the tagging of named entities, such as people and places. Using computationally-assisted parsing, i.e. Named Entity Recognition (NER), Perseus published in 2008 English translations of its Greek and Latin corpora in a TEI format with places automatically marked up, thereby enabling their extraction for analysis and mapping. Taking the English TEI text of Herodotus from Perseus, the Hestia project (2008–2010, AHRC reference AH/F019459/1) used digital technology to interrogate the spatiality of Herodotus’ Histories. As well as developing and documenting a workflow for spatial analysis from TEI text to GIS visualisation,Footnote 53 Hestia drew on contemporary geographical theory to show how an analysis of the text's topological relations between places and people can reorganise spatial understanding around power and agency, rather than on Cartesian geometry (Figure 7).Footnote 54
Mapping text has a great deal of potential. For example, Homerist J.S. Clay used a series of exhibits in the software application Neatline to reveal the different spatial configurations at play in Homer's Catalogue of Ships: most notably, the radial patterning of the Boeotian contingents around an absent Thebes.Footnote 55 Yet, where extracting place names from texts (geoparsing) is relatively trivial with NER (at least with English translations), disambiguating the names and locating each place (geo-resolution) requires far more effort, thereby making it more difficult to scale up. To address this challenge, Google Ancient Places (GAP) experimented with automating geo-resolution by linking place names in texts to entries in Pleiades, marked by identifiers unique to that place record – so-called URIs (Uniform Resource Identifiers). While achieving optimal performance from automated geo-resolution remains a distant goal, GAP's initial work not only enabled to map places mentioned in a particular work more efficiently, but also revealed the potential for analysing large corpora through their references to place.
LINKED OPEN (GEO)DATA
The launch of Pleiades, with its reorientation of the notion of place away from geometry and towards conceptual and cultural perception, coupled with the subsequent applications of spatial analysis to texts, showed that the representation of ancient space in the digital world was not limited to location and geometry data. Rather, taking place in a digital environment as multi-layered encompasses a range of discipline-specific information: cultural and literary references, language and syntax, material practices of space and travel, environmental impact, indicators of uncertainty and ambiguity, and relations to other entities in the ancient world, including people, events and objects. As well as expanding the conceptual understanding of place, Pleiades's use of gazetteer URIs also presented a technological opportunity: Linked Open Data (LOD).Footnote 56
As defined by Tim Bernes-Lee, LOD ‘is about making links, so that a person or machine can explore the web of data. With linked data, when you have some of it, you can find other, related, data’. Working with various international partners from Classical Studies (Pleiades, Perseus, the German Archaeological Institute), the Pelagios initiative (Figure 8) co-created a lightweight but universally applicable method of linking online resources through common references to places. Instead of compelling everyone to remodel their data according to an all-embracing ontology, the Pelagios method simply states that each provider should annotate the places mentioned in their data with the appropriate gazetteer URI record.Footnote 57 Helping to establish Classical Studies at the forefront of LOD innovation in the humanities, Pelagios's pioneering method has inspired the creation of other LOD infrastructures, such as pre-modern ScandinaviaFootnote 58 and the Americas, and has led to the establishment of the World Historical Gazetteer, a single platform for contributions of place name data. Equally, Pelagios has fostered an approach to digital data production that privileges information exchange across resources and contribution to publicly open and free LOD repositories such as Wikidata. Thanks to the success of LOD, scholarship in digital humanities has turned to the systematic digitisation of place names as a part of growing Linked Open (geo)Data ecosystem,Footnote 59 where agreement on data representation enables integration of interdisciplinary knowledge through the semantic web.Footnote 60
The range and diversity of Classical Studies resources publishing LO(geo)D grows year on year.Footnote 61 Early adopters such as Nomisma, the Portable Antiquities Scheme, OmnesViae and Arachne have been joined by recent EU-funded work, such as the Oxford-based projects Crossreads and Change, as well as Itiner-e, a gazetteer for Roman roads. The web and mobile application ToposText harnesses LOD connectivity to display place references found in ancient texts at minute levels of granularity, including references to ancient monuments and sites. Trismegistos combines a geographical database with systematic references to people, texts and scholarly resources focusing on ancient Egypt.Footnote 62 The Pompeii Artistic Landscape Project uses LOD to support site-wide discovery, mapping, analysis and sharing of information about Pompeian artworks in their architectural and urban contexts. MANTO takes the idea of mapping beyond the confines of the real world, by offering a digital portal based on the network software environment Nodegoat, where users can investigate the multiple connections between mythical people, places and events. Crucially, LOD achieves interconnectivity by giving researchers access to information across heterogeneous resources, hosted by different data providers: therefore, a text-based project is not limited to showing textual data, but can access information from digital libraries, museum archives, archaeological and numismatic records, and cultural heritage resources. In so doing, LOD infrastructure enables a ‘deep’ form of spatial analysis that brings together multiple layers of information.Footnote 63
In the process of extending its methodology beyond traditional Classical Studies, Pelagios developed a suite of open-source tools. To enable the production of LOD by the domain specialist or curator without need for coding expertise, Pelagios created a semantic annotation platform, Recogito.Footnote 64 Recogito facilitates the mark-up of place references in documents (texts, maps, databases), the attribution of semantic labels with tailored or external vocabularies (e.g. defining place type, cultural concepts and so on) and the geo-resolution to global authority records, such as URI-based gazetteers like Pleiades. This operation also enables the extraction of other relevant information about an individual place, such as chronological span, alternative names and mentions in other sources. Recogito has been widely adopted in research and teaching efforts focusing on places in historical sources, and even for NER to automatically identify place names.Footnote 65 In the Agathemerus project Palladino has used semantic annotation and a combined approach of network analysis and GIS to show how computational approaches can provide insights into dynamics of spatial conceptualization in scientific and periplographic geography, and even contribute to the resolution of textual corruptions (Figure 9 and 9A).Footnote 66
In 2017 Pelagios also developed an open-source visualisation tool, Peripleo, to showcase the potential of LO(geo)D connectivity. Peripleo was designed to offer a map view, where users could click on a place and explore the layers of connected information available through interlinking of partner resources, which were associated with the same place by means of gazetteer URIs. This visualisation enabled exploration of a place from a different perspective, enhancing the discovery of connected documents and artefacts.Footnote 67
At the end of the last funding round of Pelagios in 2019, the project was re-established as a free open infrastructure, the Pelagios Network, where equal partners share knowledge and expertise among different disciplinary groups, driving development of LOD tools and methods. Within this framework of ‘distributive resilience’,Footnote 68 Peripleo was reconfigured as an open browser-based tool to host custom LOD visualisations (https://github.com/britishlibrary/peripleo), after initial redevelopment undertaken by the partner project Digital Periegesis. The Digital Periegesis uses Recogito to annotate references to places, people and events in the Greek text of Pausanias’ Periegesis Hellados and leverages LOD technology to connect the narrative to the spaces it describes. The geo-resolution of individual places to gazetteer URI records allows the reading of the text in dialogue with a mapped visualisation of the spaces mentioned, but also to explore those spaces and the objects (sites, artefacts, stories) located in them through links to external online resources, such as museum collections, digital libraries and archaeological databases (Figure 10). In this way, Pausanias’ description can be better contextualised, while the process of bringing together other information can shed light on understanding that description and its function within the narrative.Footnote 69 The Digital Periegesis offers a test case of LOD as a mechanism to combine different information layers and disciplinary practices through the notion of place.
CURRENT CHALLENGES AND POSSIBLE WAYS FORWARD
In this overview we have presented the current state of spatial analysis in Classical Studies using digital methods and tools. While there have been massive strides in recent years, stimulated and supported by cross-disciplinary innovations, there are still considerable challenges to overcome.
Many parts of the ancient world still lack digital resources. There is yet no full gazetteer for first-millennium Babylonian placenames and water bodies.Footnote 70 Crucially, digital (and print) authoritative references for ancient personal names are almost completely missing.Footnote 71 Working directly on primary sources in the original language, as in the case of the Digital Periegesis, is a relatively new operation and very time-consuming. New methods to perform Named Entity Recognition, i.e. the automatic extraction of place and personal names, are currently being developed leveraging AI and multilingual models, particularly for Latin and ancient Greek,Footnote 72 and it remains to be seen what impact they will have. Likewise, while semantic annotation is a tremendously powerful tool to associate concepts to places, there is a lack of common vocabularies to refer to such concepts in ancient texts, and this creates many obstacles to sharing and reusing the data created in individual projects.Footnote 73
The increasing digitisation of the past does not come without ethical concerns. Just as Cartesian maps are at odds with ancient spatial perceptions, increasing digitally open access information about ancient sites is at risk of exposing information of crucial importance to indigenous communities, not to mention facilitating trade in illicit antiquities. The imposition of the same standards and technologies on the highly diverse civilisations and knowledge systems that fall under the blanket term of ‘antiquity’ is also epistemologically problematic.Footnote 74 As technology advances, these are questions that scholars of the past will have to keep addressing.Footnote 75
Finally, the rapidly growing interdisciplinarity of the methods applied in the digital representation of ancient space is complemented by an increasing diversity of data, including not only texts and maps, but also databases, 3D and virtual reconstructions, audio and video media etc. Such multimediality points to a transformation in academic practice, with an increasing awareness of the need to use, incorporate or at least acknowledge very different types of data, when the traditional monograph-focused publication (still) holds sway in the minds of publishers and tenure committees. There is also a need for greater visual literacy, to help scholars read visual and mapped data, both ancient and modern. Ultimately, when everything can, in principle, be linked, what intellectual choices are to be made about what should be linked? And what design choices are to be made about how to better surface those links? Networks? Deep maps? Whatever form Spatial Classics takes, collaboration – between Classicists, with other disciplines both in and external to the humanities – will play a critical role.
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What might our student reading the same Odyssey passage see in the year 2043?
Now the interface does not just provide a list of names and a map. A more refined set of annotations on the text provide better clarifications to the places mentioned in the passage: the ‘wine-dark sea’ is identified and mapped to the Aegean Sea, while several alternative locations are provided for the debated identification of the Pelasgians. Different map layer options show the shifting location of ancient Knossos through history, and its spatial relation to the road and sea network. Clicking on ‘Deucalion’ does not open a Wikipedia page but a scholarly resource of classified mythical names, providing a family tree, a network of places and people connected to the king of Crete, as well as further links to their stories in other ancient works or their depictions on artefacts preserved in museums. Satellite images show archaeological sites in the island, the changes of the terrain and hydrographic structure through time; there is a link to a numismatic repository illustrating the different coinages and mints of the island through history, and to an epigraphic collection showing inscriptions from the area through different times. Clicking on ‘Crete’ populates a network of places mentioned in the Odyssey, to illustrate how many times the island is mentioned and what kinds of relationships are established with other people and places throughout the work. Clicking on ‘Cydonia’ triggers an online gazetteer entry, where the student can inspect other ancient mentions of the place tagged in other digital editions, descriptions and photos of its monuments, and links to other projects illustrating the history of the place during the Minoan, Byzantine and Ottoman Turkish domination. So many different routes, so many different stories to explore.