This deliverable describes the first version of the 5G-EPICENTRE federated experimentation facility architecture, along with a comprehensive set of the stakeholders’ experimentation requirements elicited using online survey tools and questionnaires. A second, updated version of the contents of this deliverable will be provisioned at M24.The intention of this document is to provide a comprehensive overview of the facility technical specifications, along with a functional viewpoint of the architectural building blocks that will comprise the final platform to be delivered. Therefore, no specific implementation detail will be implied in this document, rather a high-level overview of the envisioned roles, responsibilities and interrelationships among platform components will be documented to be used as guidelines for the development of the individual technological components in the context of WPs 2-4. A more elaborate description of the framework with initial interface descriptions will be provided in the context of the facility framework documentation due in M12 (D4.1), while the reference implementation will be provided in the updated version of this deliverable (D1.4) due M24.This document will provide a thorough description of the methodology and tools used to elicit the platform stakeholders’ (i.e., experimenters expected to utilise the platform for the purpose of experimenting with their solutions) requirements, which have been analysed and classified into a comprehensive set of high-level functional and non-functional requirements for the 5G-EPICENTRE prototype integrated experimentation facility.In addition, the document presents the methodology to define the architectural model, namely the various stages of the architecture design approach. These constitute a technology exploration step, followed by a top-down design approach and finally complemented by a bottom-up thorough specification of identified functional blocks. We then elaborate on the cloud-native approach, providing implementation reference frames for embracing cloud-native in the form of lightweight virtualisation technology (containers) and container orchestration tooling. Implications of the cloud-native approach to VNF orchestration on the ETSI-specified NFV-MANO architecture are thoroughly discussed.Finally, three architectural viewpoints are defined, namely the functional view, information view and deployment view. The first specifies the roles and capabilities provided by the various functional blocks identified in the design process. The second defines a number of reference points as placeholders for the elaboration of component interfaces and cross-layer aspects in the context of T4.1. Finally, the third provides insight on deployment of the hardware and software artefacts, a process that will be thoroughly documented in the updated version of this document.