The SyMoGIH project has created an open modular platform for storing geo-historical information. The benefit of the platform is to allow researchers to share their data and texts in a collaborative environment. We also created a generic website to deliver to the public the whole of our authority files and the knowledge units which the participating scholars decided to make public (www.symogih.org). We are preparing the publishing of our data with semantic web technologies. The poster presents the issue of developing a project specific ontology, and interlinking it with existing and commonly used ones, and the technology we intend to use.