Pelagios 4: studying the places of our past through the Early Geospatial Documents that refer to them

Being able to link - to go from one document to another - is one of the great facilitating features of the World Wide Web. It is how you are able to find out more about or get a different perspective on something that interests you at the click of a mouse. But how are these linkages enabled? Since 2011 Pelagios (http://pelagios-project.blogspot.com/) has been developing the means of linking independently created and hosted online resources together via their common references to place. This Linked Open Data approach essentially means: (i) having your document (whether that is a text, image, map or database, etc.) openly online; (ii) annotating ('tagging') all place references in the metadata that underlies your online document; and (iii) aligning those references to a Web-based gazetteer service that provides a unique global identifier (i.e. a unique code number) for individual places in the world. These annotations collectively form a Web-based network connecting documents to places and thus to one another. By these means, Pelagios has been playing a crucial role in creating a World Wide Web of antiquity, whereby scholars, students, cultural heritage providers or general enthusiasts can not only make their resources more discoverable and usable, but also enable others to find out about the cities of antiquity and explore the rich interconnections between them.

Pelagios 4 builds on this essential infrastructural work to reflect on 5 key moments in the story of the history of geographic representation. In the pre-modern European and Mediterranean world (i.e. before the discovery of the Americas), geographic space was represented in a variety of ways - computational measurements of early Greek and Latin literature; accounts of sea voyages in the Mediterranean and Black Sea; itineraries of land routes in the Late Roman Empire; seafaring maps of coastlines from mediaeval Europe; and mediaeval pilgrimage literature. This project focuses on these sources and their contexts in order to identify and explore the many different ways in which the world was viewed and understood, before the development of standardizing global cartographic conventions (such as the Mercator projection) that followed the European discovery of the Americas in 1492. Taken together, these sources provide invaluable testimony to lost ways of thinking about the world that may serve to challenge our standardized image, which, if anything, has become even more dominant in the age of Google Maps and Google Earth. Yet, previously the study of Early Geospatial Documents has suffered from the difficulty of accessing the sources (particularly old maps) and finding information about places buried deep in lengthy texts. Due to digitization efforts, it is now possible to access these different kinds of information; and, thanks to Pelagios, these materials can now be easily linked together and aggregated, enabling texts to be read against other types of source (maps, archaeological data, etc.) and vice versa.

Using the enriched context that Pelagios's Linked Open Data provides to these Early Geospatial Documents, Pelagios 4 will work with expert scholars to bring out the distinctive contribution of each type of document to the development of geospatial knowledge production from antiquity through to the mediaeval period. In particular we will be keen to address the continuities and discontinuities in conceptions of geographic space, the comparison of these ancient witnesses to the archaeological record, and the difference between textual and pictorial representation of space.

To date, Pelagios has shown itself to be interesting to a variety of parties beyond academia:
- Content sharers: Pelagios partners a number of institutions beyond Higher Education, including the British Museum, the British Library, The International Association for Classical Archaeology (AIAC) and the American Numismatic Society.
- News organizations: Pelagios has been featured in a variety of online news outlets including The Guardian, Russia Today and El Pais (Uruguay).
- Online portals: The online Spanish language classics portal Portal Clásico described the Pelagios interface as "the closest thing we've ever experienced to going back in time and knowing the landscape as it was in Antiquity" (http://portalclasico.com/proyectos-pelagios-el-mapa-virtual-del-imperio-romano).
- The Pelagios Team has provided consultation on Linked Open Data approaches to cultural heritage for a variety of organizations including the German Archaeological Institute, the Max Planck Institute for the History of Science, the Getty Conservation Institute, the World Monuments Fund, the Linked Ancient World Data Institute, English Heritage, the British Library, the British Museum, Ordnance Survey, and Wikidata.
- Private individuals: There have been multiple expressions of interest from the general public worldwide, either to join our network (http://vici.org/) or to volunteer to help build our annotations.

The reasons for this interest are varied:
- Value Addition: Resource Providers are able to enrich and contextualise their content more easily.
- Discovery: Resource providers are more likely to be found due to increased number of incoming links.
- Serendipity: users are more likely to encounter related content by chance, without having originally sought it.
- The Pleasure principle: many users (and the Pelagios team) enjoy playing with Pelagios data and finding new and unexpected patterns within it.
- Cultural connections: The wide geographic breadth, visual appeal, and emphasis on the historic transience of borders, along with a limited emphasis English text, make Pelagios relevant to people from a very wide (and increasing) range of countries, and encourage them to reconsider the world without contemporary borders.

Pelagios 4 will continue to work with these partners in enabling teachers, students, policy makers, memory institutions and general enthusiasts to benefit more directly from our digital data and tools and to explore the ancient and pre-modern worlds in new and exciting ways. These benefits operate on multiple levels. The ability to spatially locate people, places and events is extremely important for the comprehension of almost any ideas about historical development: Pelagios 4 will facilitate this process by allowing non-specialist or technical users (other researchers, teachers, students or the general enthusiast) to see how individual accounts refer to specific places, in contrast to the high level synthetic overviews typically found in secondary literature, whether written or drawn for a scholarly or lay audience.

At a deeper level the graph of connections between such sources will allow users to discover contextualizing related material. Because Linked Open Data is Web based, such resources are instantly accessible, reducing the barriers to entry which currently impede public engagement. This will be of significant benefit to Content Providers hosting EGDs who should not only see a rise in traffic but, by tracing its source, will be able to show directly its value within academic research. Content providers hosting data related to the places referred to in EGDs should also see increased use as users 'explore' the data. Policy makers, such as JISC, will benefit from several concrete examples of how Linked Open Data can be used to support the Arts and Humanities. Public agencies like Ordnance Survey will benefit from real use cases of spatial indexing and querying.