Deliverable D11.1 presents the pilot definition and design work carried out in Work Package 11 of the ARTEMIS project. Its purpose is to document the pilot portfolio that will be used to demonstrate, validate and test the ARTEMIS approach to Reactive Heritage Digital Twins (RHDT) in realistic cultural heritage (CH) contexts. In ARTEMIS, pilots are not treated as isolated demonstrations but as a mechanism for specifying practical use cases, required data, services, workflows and validation needs. The deliverable establishes the common methodological framework used to move from initial pilot ideas to structured pilot definitions that are based on a common documentation structure focused on each case study, their objectives, technologies and tools, data resources, integration requirements and evaluation metrics. D11.1 presents a portfolio of sixteen pilots organised into small-, medium- and large-scale categories, following the ARTEMIS Description of Action document. As a whole these pilots cover a broad range of CH assets, stakeholders and operational needs, from movable artefact-level documentation and monitoring to building-scale analysis, urban simulation and large-scale risk assessment. The sixteen pilots described in this deliverable also clarify the relationship between the ARTEMIS’ pilot-number commitment and the RHDT demonstrator KPI. The DoA describes at least fifteen pilots addressing different CH-related case studies, while the KPI table refers to twenty pilot demonstrators of RHDT implementations. This is addressed through the CH asset-based structure of the portfolio. In fact, several of the pilots include more than one CH asset. Consequently, the sixteen defined pilots provide a broader set of CH assets and context instances from which the twenty RHDT demonstrators can be implemented and validated in the second half of the project.