This poster describes the NFDI4Culture Ontology (CTO). It is being presented at the International Semantic Web Conference 2025 in Nara, Japan. Within the National Research Data Infrastructure (NFDI) in Germany, the NFDI4Culture consortium addresses a critical challenge: unifying access to fragmented and semantically heterogeneous cultural heritage (CH) research data scattered across institutions and disciplines. This work presents the NFDI4Culture Ontology (CTO), a strategically designed lightweight, BFO-aligned ontology that successfully bridges the gap to represent CH research resources between specialized domain requirements and interoperability demands across diverse cultural heritage fields including musicology, performing arts, and architecture. CTO extends the established mid-level ontology NFDIcore while maintaining the flexibility essential for capturing domain-specific nuances and is fully integrated into productive research data infrastructures. This contribution demonstrates how domain-specific ontologies can support both highly specialized research needs and broader cross-domain interoperability through modular architecture, and provides insights into proven modeling strategies, integration workflows, and lessons learned from a productive system in the CH domain.