CrossCult is an EU-funded research project aiming to spur a change in the way European citizens appraise History, fostering the re-interpretation of what they may have learnt in the light of cross-border interconnections among pieces of cultural heritage, other citizens’ viewpoints and physical venues. Exploiting the expressive power, reasoning and interoperability capabilities of semantic technologies, the CrossCult Knowledge Base models and semantically links desperate pieces of Cultural Heritage information, contributing significantly to the aims of the project. This paper presents the structure, design rationale and development of the CrossCult Knowledge Base, aiming to inform researchers in Digital Heritage about the challenges and opportunities of semantically modelling Cultural Heritage data.