Research infrastructures in the Humanities and Cultural Heritage increasingly operate within complex digital ecosystems, where data, tools, services, and communities continuously evolve. In this context, access-oriented platforms alone are no longer sufficient: infrastructures also require analytical instruments capable of monitoring practices, identifying trends, and supporting evidence-based decision making. This paper presents the H2IOSC Observatory, a permanent monitoring environment developed within the Humanities and Heritage Italian Open Science Cloud (H2IOSC), and discusses its design as a joint effort of four European Research Infrastructures: CLARIN, DARIAH, E-RIHS, and OPERAS.

The H2IOSC Observatory is conceived as a dynamic monitoring layer that complements infrastructural service provision. It builds on an extensive landscape activity carried out through a mixed-methods approach combining large-scale surveys, semi-structured interviews, focus groups, and systematic mapping of digital resources, tools, projects, and services. Rather than producing a static landscape report, these methods are operationalised within a continuously updated web-based Observatory designed to support long-term monitoring of research practices, FAIRness levels, infrastructural uptake, and community needs.

A central aspect of the design is the tight integration between the H2IOSC Observatory and the H2IOSC Marketplace. While the Marketplace provides access to datasets, tools, and services, the Observatory analyses their distribution, evolution, and use over time. This bidirectional relationship enables the Observatory to inform Marketplace curation strategies, onboarding priorities, and service design, while usage data and resource metadata feed back into the analytical layer. Together, the two platforms form a coupled system linking resource provision and evidence-based monitoring.

A defining feature of the Observatory is its cross-infrastructure and cross-domain architecture. Each participating Research Infrastructure contributes domain-specific perspectives and datasets: CLARIN brings expertise in linguistic resources and metadata aggregation; DARIAH contributes digital humanities methods, tools, and community-driven workflows; E-RIHS provides heritage science datasets and data spaces; OPERAS contributes knowledge on open scholarly communication and publishing practices. The Observatory integrates these heterogeneous inputs into a shared analytical framework, enabling comparative analysis while preserving disciplinary and methodological diversity. This coordinated approach demonstrates how multiple infrastructures can jointly construct a common monitoring environment without enforcing homogenisation.

The paper focuses in particular on the conceptual and functional characteristics of the Observatory. Structurally, it is organised as a modular web application providing interactive dashboards, qualitative summaries, and aggregated indicators derived from both quantitative and qualitative sources. Methodologically, it combines statistical analysis with interpretive layers that contextualise metrics within community practices. From a governance perspective, the Observatory supports evidence-based coordination across infrastructures by providing shared indicators, feedback mechanisms, and monitoring tools that inform strategic planning, service evolution, and the identification of gaps and FAIRification priorities.

The paper concludes by arguing that the H2IOSC Observatory contributes to the long-term sustainability of Humanities research infrastructures by embedding continuous, community-driven monitoring into their governance and evolution. By making its methodologies explicit and its results openly accessible, the Observatory aligns with Open Science principles and contributes to current debates not only within the DARIAH community, but also across the wider research infrastructure community and the broader EOSC landscape.