ChronOntology - A Time Gazetteer for the Historical-Cultural Studies Subjects

Exemplary presentation of time concepts i3mainz, CC BY SA 4.0

The aim of ChronOntology is to provide persistent open web services for dynamically addressing the whole range of chronological concepts as Linked Open Data resources, analogous to location data in a gazetteer. The published chronological information should make it possible to assign standardised time assignments to digital resources in the Digital Humanities.


The successfully established gazetteer systems and services such as Pleiades and Pelagios make it possible to link humanities text and object data with unambiguous and persistently addressable location information. However, the temporal dimension of the information in its historical development remains largely unconsidered. A major desideratum is therefore a URI-based method for dynamically addressing the whole range of chronological concepts as Linked Open Data resources via web services, with CIDOC CRM, Dublin Core and RDF-based representation options.

The goal of ChronOntology is the persistent provision of such open web services. The API provides semantically modelled resources on standardised time information under a URI, analogous to location data in a gazetteer. These uniformly addressable time specifications enable the linking of digital knowledge resources of the Digital Humanities with standardised time allocations.

The task of i3mainz in the ChronOntology project is to ensure the adequate representation and visualisation of place references within the time concepts. For example, the term “Early Bronze Age” encompasses very different archaeological phenomena depending on the region. These boundaries are blurred and only emerge from the evaluation of the data material.

The web provides further space-time gazetteers in projects such as PeriodO or Geodia. In contrast to PeriodO, whose concepts of time are based on literature sources, ChronOntology is based on real object data such as the Arachne database of the DAI.


The work in the second year of the project focused on visualisation strategies of temporal and spatial relations in widgets available online. These are both directly integrated by the frontend, but should also be able to be adopted independently in third-party systems.

Special attention is paid to the ChronOntology Time Browser developed by Sebastian Cuy and Wolfgang Schmiedle, which makes complex hierarchies of linked periods available in a user-friendly way. Florian Thiery implements the ChronOntology Geo Widget, which functions as a central visualisation of the spatial context and their semantic relationship. This widget for the integration of the linked semantic information of the iDAI.gazetteer is based on JAVA Servlets and Leaflet. In addition, items from the Arachne object database that are linked to ChronOntology are currently displayed. This results in real distribution maps directly from the underlying subject data.

Wolfgang Schmiedle presented the first results of the project in collaboration with Florian Thiery, Nathalie Kallas and Sebastian Cuy at the CAA 2016 in Oslo in the lecture “Linking periods: Modelling and utilising spatio-temporal concepts in the ChronOntology project”. The ChronOntology Server ( was also published here. In December, Kai-Christian Bruhn accepted the invitation of the Pelagios Commons to the “2nd International Linked Pasts Symposium” at the Facultad de Filología, UNED, Madrid, to present higher-level considerations on the linking of time concepts.

In 2017, further development of the Time and Geo widgets, the creation of “Space Time Volumes” and the release of the ChronOntology Server are planned. The Time Gazetteer will be available to the research community and the source code will be published on GitHub so that institutions can publish their own instance of the Time Gazetteer.