This white paper summarizes the main findings from the European research landscape on the vision of the 6G architecture. Such a design vision is derived from around 45 projects starting from October 2020 in all relevant areas of 5G while paving the way towards 6G, within the 5G Public Private-Partnership (5G PPP) in the scope of the European Framework for Research and Innovation (the list of contributing projects can be obtained from the 5G PPP website at https://5g-ppp.eu/5g-ppp-phase-3-projects/.). At present, the European networking research community has started a new program along with 33 projects on the Smart Networks and Service (SNS) programme that will focus on 5G advanced and 6G. The 5G/B5G Architecture Working Group (WG), as part of the 5G PPP Initiative, is identifying and capturing novel trends and key technological enablers for the realization of the 5G and 6G architecture. The main findings and results of the Architecture WG are now captured in this white paper, which presents a consolidated view from European perspective on the technical directions for the architecture design in the 6G era. The white paper starts with an analysis of the societal, economic, regulatory and technological trends on the design and development of future 6G networks towards 2030 and beyond. Infused by emerging and disruptive digital technologies on the horizon, wireless networks are and will be the keystone for enabling a transformation of the global economy and the evolution of human society. The evolution journey will carry on in the years ahead, driving a large scale of adoption of 5G and 5G-Advanced use cases with significantly decreased deployment and operation costs, and enabling new and innovative use-case-driven solutions towards the 6G with higher economic and societal values. To realize aforementioned trends, this white paper highlights the related research work and presents all the key elements and key architecture enablers and solutions of future 6G network design; a design that is deeply rooted in real needs and can profoundly benefit humanity in the mid-to-long term. Specifically, a high-level view of the 6G End-to-End architecture as well as a functional view of the 6G reference architecture are introduced in this white paper, taking into consideration of new stakeholders in the mobile network ecosystem and how the architectural work is taking into account their requirements in all the domains of the network. The key architecture enablers, that will form the backbone of future 6G network architecture, includes all the related technological solutions for building intelligent, flexible, sustainable, secure, programmable networks and enabling versatile radio technologies, localization and sensing in the 6G networks.